History of Korea

The Paleolithic period of Korea is the earliest known prehistoric era of the Korean Peninsula, spanning from around 500,000 to 10,000 years ago. This era is characterized by the emergence and use of stone tools by early human ancestors. Sites across the Korean Peninsula have yielded primitive choppers, handaxes, and other stone implements which provide evidence of the early human habitation and their adaptability to the environment.

Over time, the tools and artifacts from this period evolved in complexity, reflecting advancements in tool-making techniques. The early Paleolithic sites often reveal tools made from river pebbles, while the later Paleolithic sites show evidence of tools crafted from larger stones or volcanic material. These tools were primarily used for hunting, gathering, and other daily survival activities.

Furthermore, the Paleolithic period in Korea is significant for its insights into the migration and settlement patterns of early humans. Fossil evidence suggests that early humans migrated to the Korean Peninsula from other parts of Asia. As the climate changed and became more hospitable, these populations settled, and distinct regional cultures began to emerge. The end of the Paleolithic period marked a transition to the Neolithic era, where pottery and agriculture started to play a more central role in daily life.

The Jeulmun pottery period, spanning from 8000–1500 BCE, encapsulates both the Mesolithic and Neolithic cultural phases in Korea.^[8] This era, sometimes referred to as the "Korean Neolithic," is renowned for its decorated pottery vessels, especially prominent from 4000-2000 BCE. The term "Jeulmun" translates to "Comb-patterned." This period reflects a lifestyle dominated by hunting, gathering, and small-scale plant cultivation.^[9] Notable sites from this era, such as Gosan-ni in Jeju-do Island, suggest the origins of the Jeulmun could trace back as far as 10,000 BCE.^[10] The significance of the pottery from this period is underscored by its potential to be among the world's oldest known pottery forms.

The Early Jeulmun, from approximately 6000-3500 BCE, was characterized by hunting, deep-sea fishing, and the establishment of semi-permanent pit-house settlements.^[11] Key sites from this period, such as Seopohang, Amsa-dong, and Osan-ri, offer insights into the daily lives and subsistence practices of the inhabitants. Interestingly, evidence from coastal regions like Ulsan Sejuk-ri and Dongsam-dong indicates a focus on shellfish gathering, although many archaeologists believe these shellmound sites emerged later in the Early Jeulmun.^[12]

The Middle Jeulmun period (c. 3500-2000 BCE) provides evidence of cultivation practices.^[13] Notably, the Dongsam-dong Shellmidden site has produced direct AMS dating of a domesticated foxtail millet seed to this era.^[14] However, despite the emergence of cultivation, deep-sea fishing, hunting, and shellfish gathering remained significant aspects of subsistence. The pottery of this period, known as "Classic Jeulmun" or Bitsalmunui pottery, is distinguished by its intricate comb-patterning and cord-wrapping decorations, which cover the entire vessel surface.

The Late Jeulmun period, from around 2000-1500 BCE, witnessed a shift in subsistence patterns, with a reduced emphasis on shellfish exploitation.^[15] Settlements started appearing inland, such as Sangchon-ri and Imbul-ri, suggesting a move towards cultivated plant reliance. This period runs parallel to the Lower Xiajiadian culture in Liaoning, China.

As the Late Jeulmun era waned, the inhabitants faced competition from newcomers proficient in slash-and-burn cultivation and using undecorated Mumun pottery. This group's advanced agricultural practices encroached upon the traditional hunting grounds of the Jeulmun people, marking a significant shift in the cultural and subsistence landscape of the region.

The Mumun pottery period, spanning from approximately 1500-300 BCE, is a significant era in Korean prehistory. This period is primarily identified by its undecorated or plain cooking and storage vessels that were prominent especially between 850-550 BCE. The Mumun era marked the commencement of intensive agriculture and the evolution of complex societies in both the Korean Peninsula and the Japanese Archipelago. Despite being occasionally labeled as the "Korean Bronze Age", this classification can be misleading since local bronze production began much later, around the late 8th century BCE, and bronze artifacts were scarcely found during this period. A surge in archaeological explorations since the mid-1990s has enriched our understanding of this pivotal period in East Asian prehistory.^[16]

Preceded by the Jeulmun Pottery Period (c. 8000-1500 BCE), which was characterized by hunting, gathering, and minimal cultivation, the Mumun period's origins are somewhat enigmatic. Significant findings from the Liao River Basin and North Korea from around 1800-1500 BCE, such as megalithic burials, Mumun pottery, and large settlements, possibly hint at the Mumun Period's initiation in Southern Korea. During this phase, individuals who practiced slash-and-burn cultivation using Mumun pottery seemed to have displaced those following the Jeulmun Period subsistence patterns.^[17]

The Early Mumun (c. 1500-850 BCE) was marked by shifting agriculture, fishing, hunting, and the emergence of distinct settlements with rectangular semi-subterranean pit-houses. The settlements from this era were predominantly located in the river valleys of West-central Korea. By the end of this sub-period, larger settlements began appearing, and long-standing traditions related to Mumun ceremonial and mortuary systems, such as megalithic burials and red-burnished pottery production, started taking shape. The Middle Mumun (c. 850-550 BCE) saw the rise of intensive agriculture, with vast dry-field remains discovered at Daepyeong, a significant settlement site. This period also witnessed the growth of social inequality and the development of early chiefdoms.^[18]

The Late Mumun (550-300 BCE) was characterized by an increase in conflict, fortified hilltop settlements, and a higher concentration of the population in the southern coastal regions. There was a noticeable reduction in the number of settlements during this period, possibly due to increased conflict or climatic changes leading to crop failures. By approximately 300 BCE, the Mumun period came to an end, marked by the introduction of iron and the appearance of pit-houses with internal composite hearth-ovens reminiscent of the historical period.^[19]

The cultural traits of the Mumun era were diverse. While the linguistic landscape of this period suggests influences from both Japonic and Koreanic languages, the economy was largely based on household production with some instances of specialized craft production. The Mumun subsistence pattern was broad, encompassing hunting, fishing, and agriculture. Settlement patterns evolved from large multi-generational households in the Early Mumun to smaller nuclear family units in separate pit-houses by the Middle Mumun. Mortuary practices were varied, with megalithic burials, stone-cist burials, and jar burials being common.^[20]

Gojoseon, also known as Joseon, was the earliest kingdom on the Korean Peninsula, believed to have been founded by the mythical king Dangun in 2333 BCE. According to the Memorabilia of the Three Kingdoms, Dangun was the offspring of the heavenly prince Hwanung and a bear-woman named Ungnyeo. While Dangun's existence remains unverified, his story holds significant importance in shaping Korean identity, with both North and South Korea celebrating Gojoseon's establishment as National Foundation Day.

The history of Gojoseon saw external influences such as Jizi, a sage from the Shang dynasty, who is said to have migrated to the northern Korean Peninsula in the 12th century BCE, leading to the founding of Gija Joseon. However, debates persist about the authenticity and interpretations of Gija Joseon's existence and its role in Gojoseon's history.^[21] By 194 BCE, the Gojoseon dynasty was toppled by Wi Man, a refugee from Yan, ushering in the era of Wiman Joseon.

In 108 BCE, Wiman Joseon faced conquest by the Han dynasty under Emperor Wu, leading to the establishment of four Chinese commanderies over the former territories of Gojoseon. This Chinese rule waned by the 3rd century, and by 313 CE, the region was taken over by Goguryeo. Wanggeom, now modern-day Pyongyang, served as Gojoseon's capital from the 2nd century BCE, while the Jin state emerged in the southern parts of the peninsula by the 3rd century BCE.^[22]

The Jin state, existing between the 4th to 2nd centuries BCE, was a confederation of statelets in the southern part of the Korean peninsula, neighboring the Gojoseon kingdom to the north.^[23] Its capital was located somewhere south of the Han River. While the exact organizational structure of Jin as a formal political entity remains uncertain, it appears to have been a federation of smaller states, similar to the later Samhan confederacies. Despite the uncertainties, Jin's interactions with Wiman Joseon and its attempts to establish diplomatic ties with the Western Han dynasty indicate some degree of stable central authority. Notably, after Wiman usurped his throne, King Jun of Gojoseon is said to have sought refuge in Jin. Moreover, some scholars believe that the Chinese references to Gaeguk or Gaemaguk could pertain to Jin.^[24]

The downfall of Jin is a topic of debate among historians.^[25] Some records suggest that it evolved into the Jinhan confederacy, while others argue that it branched out to form the broader Samhan, encompassing Mahan, Jinhan, and Byeonhan. Archeological findings related to Jin have been predominantly discovered in areas that later became part of Mahan. The Chinese historical text, Records of the Three Kingdoms, asserts that Jinhan was the direct successor of Jin. In contrast, the Book of the Later Han posits that Mahan, Jinhan, and Byeonhan, along with 78 other tribes, all originated from the Jin state.^[26]

Despite its dissolution, the legacy of Jin persisted in the subsequent eras. The name "Jin" continued to resonate in the Jinhan confederacy and the term "Byeonjin," an alternate name for Byeonhan. Additionally, for a certain period, the leader of Mahan adopted the title "Jin king," symbolizing a nominal supremacy over the tribes of Samhan.

The Four Commanderies of Han were Chinese commanderies established in the northern Korean Peninsula and part of the Liaodong Peninsula from the end of the second century BCE through the early 4th century CE. They were set up by Emperor Wu of the Han dynasty in the early 2nd century BCE after he conquered Wiman Joseon, and were seen as Chinese colonies in the former Gojoseon region, reaching as far south as the Han River. Lelang, Lintun, Zhenfan, and Xuantu were the commanderies created, with Lelang being the most long-lasting and a significant center of cultural and economic exchange with subsequent Chinese dynasties. Over time, three of the commanderies fell or retreated, but Lelang remained for four centuries, influencing the native population and eroding the fabric of Gojoseon society. Goguryeo, founded in 37 BCE, began absorbing these commanderies into its territory by the early 5th century.

Initially, after Gojoseon's defeat in 108 BCE, the three commanderies of Lelang, Lintun, and Zhenfan were established, with Xuantu Commandery being founded in 107 BCE. By the 1st century CE, Lintun merged into Xuantu, and Zhenfan into Lelang. In 75 BCE, Xuantu moved its capital due to local resistance. The commanderies, especially Lelang, established trade relations with neighboring Korean states like Jinhan and Byeonhan. As indigenous groups integrated with Han culture, a unique Lelang culture emerged in the 1st and 2nd centuries CE.

Gongsun Du, a significant figure from the Liaodong Commandery, expanded into Goguryeo territories and exerted dominance in the northeast. His reign saw confrontations with Goguryeo and expansions into its lands. After his death in 204, his successors continued to assert their influence, with Gongsun Kang even annexing parts of Goguryeo in the early 3rd century. However, by the late 3rd century, Sima Yi of Cao Wei invaded and took over their territories. Following the fall of the Han commanderies, Goguryeo grew stronger, eventually conquering the Lelang, Daifang, and Xuantu commanderies by the early 300s.

Samhan, also known as the Three Han, refers to the Byeonhan, Jinhan, and Mahan confederacies that arose in the 1st century BCE during the Proto–Three Kingdoms of Korea. These confederacies, located in the central and southern parts of the Korean Peninsula, later evolved into the kingdoms of Baekje, Gaya, and Silla. The term "Samhan" is derived from the Sino-Korean word "Sam" meaning "three" and the Korean word "Han" which denotes "great" or "large." The name "Samhan" was also used to describe the Three Kingdoms of Korea, and the term "Han" is still prevalent in various Korean terms today. However, it is distinct from the Han in Han Chinese and the Chinese kingdoms and dynasties also referred to as Han.

The Samhan confederacies are believed to have emerged after the fall of Gojoseon in 108 BCE. They are generally perceived as loose groupings of walled-town states. Mahan, the largest and earliest of the three, was situated in the southwest and later became the foundation for the Baekje Kingdom. Jinhan, comprising 12 statelets, gave rise to the Silla Kingdom and is thought to have been located east of the Nakdong River valley. Byeonhan, also consisting of 12 statelets, led to the formation of the Gaya confederacy, which was later incorporated into Silla. The exact territories of the Samhan confederacies are a matter of debate, and their boundaries likely shifted over time. Settlements were typically built in secure mountain valleys, and transportation and trade were facilitated mainly through river and sea routes.

The Samhan era saw the systematic introduction of iron to the southern Korean peninsula, leading to advancements in agriculture and the manufacture and export of iron products, particularly by the Byeonhan states. This period also witnessed the growth of international trade, especially with the Chinese commanderies established in the erstwhile Gojoseon territories. Trade with emerging Japanese states involved the exchange of Japanese ornamental bronzeware for Korean iron. By the 3rd century, trade dynamics shifted as the Yamatai federation in Kyūshū gained control over Japanese trade with Byeonhan.

Buyeo,^[27] also known as Puyŏ or Fuyu,^[28] was an ancient kingdom located in northern Manchuria and modern-day northeast China between the 2nd century BCE to 494 CE. It is sometimes recognized as a Korean kingdom due to its ties with the Yemaek people, considered precursors to modern Koreans.^[29] Buyeo is viewed as a significant predecessor to the Korean kingdoms of Goguryeo and Baekje. Initially, during the later Western Han period (202 BCE – 9 CE), Buyeo was under the jurisdiction of the Xuantu Commandery, one of the Four Commanderies of Han.^[30] However, by the mid-1st century CE, Buyeo emerged as a crucial ally of the Eastern Han dynasty, serving as a buffer against threats from the Xianbei and Goguryeo. Despite facing invasions and political challenges, Buyeo maintained a strategic alliance with various Chinese dynasties, reflecting its significance in the region.^[31]

Throughout its existence, Buyeo faced multiple external threats. An invasion by the Xianbei tribe in 285 led to the relocation of its court to Okjeo. The Jin dynasty later assisted in restoring Buyeo, but the kingdom underwent further decline due to attacks from Goguryeo and another Xianbei invasion in 346. By 494, under pressure from the rising Wuji tribe (or Mohe), the remnants of Buyeo moved and eventually surrendered to Goguryeo, marking its end. Notably, historical texts like the Records of the Three Kingdoms highlight the linguistic and cultural ties between Buyeo and its southern neighbors, Goguryeo and Ye.

The legacy of Buyeo persisted in subsequent Korean kingdoms. Both Goguryeo and Baekje, two of the Three Kingdoms of Korea, regarded themselves as the successors of Buyeo. King Onjo of Baekje was believed to be a descendant of King Dongmyeong, the founder of Goguryeo. Furthermore, Baekje officially renamed itself Nambuyeo (South Buyeo) in 538. The Goryeo dynasty also acknowledged its ancestral ties to Buyeo, Goguryeo, and Baekje, signifying the lasting influence and legacy of Buyeo in shaping Korean identity and history.

Okjeo, an ancient Korean tribal state, existed in the northern Korean peninsula from potentially the 2nd century BCE to the 5th century CE. It was divided into two main regions: Dong-okjeo (Eastern Okjeo), covering the area of present-day Hamgyŏng provinces in North Korea, and Buk-okjeo (Northern Okjeo), located around the Duman River region. While Dong-okjeo was often simply referred to as Okjeo, Buk-okjeo had alternate names such as Chiguru or Guru, with the latter also being a name for Goguryeo.^[32] Okjeo neighbored the minor state of Dongye to its south and had a history interwoven with larger neighboring powers like Gojoseon, Goguryeo, and various Chinese commanderies.^[33]

Throughout its existence, Okjeo experienced alternating periods of dominance by Chinese commanderies and Goguryeo. From the 3rd century BCE to 108 BCE, it was under Gojoseon's control. By 107 BCE, the Xuantu Commandery exerted its influence over Okjeo. Later, as Goguryeo expanded, Okjeo became part of the eastern Lelang Commandery. The state, due to its strategic location, frequently served as a refuge for neighboring kingdoms; for instance, Goguryeo's King Dongcheon and the Buyeo court sought shelter in Okjeo during invasions in 244 and 285, respectively. However, by the early 5th century, Gwanggaeto the Great of Goguryeo had fully conquered Okjeo.

Cultural information about Okjeo, though sparse, suggests that its people and practices bore resemblances to those of Goguryeo. The "Samguk Sagi" describes Eastern Okjeo as a fertile land nestled between the sea and mountains, and its inhabitants as brave and skilled foot soldiers. Their lifestyle, language, and customs—including arranged marriages and burial practices—shared similarities with Goguryeo. The Okjeo people interred family members in a single coffin and had child-brides live with their groom's family until reaching adulthood.

The Three Kingdoms of Korea, comprising Goguryeo, Baekje, and Silla, vied for dominance over the Korean Peninsula during the ancient period. These kingdoms emerged after the fall of Wiman Joseon, absorbing smaller states and confederacies. By the end of the Three Kingdoms period, only Goguryeo, Baekje, and Silla remained, having annexed states like Buyeo in 494 and Gaya in 562. Together, they occupied the entire peninsula and part of Manchuria, sharing a similar culture and language. Buddhism, introduced in the 3rd century CE, became the state religion of all three kingdoms, starting with Goguryeo in 372 CE.^[34]

The Three Kingdoms period culminated in the 7th century when Silla, allied with China's Tang dynasty, unified the peninsula. This unification followed the conquests of Gaya in 562, Baekje in 660, and Goguryeo in 668. However, post-unification saw the establishment of a brief Tang dynasty military government in parts of Korea. Silla, supported by Goguryeo and Baekje loyalists, resisted Tang dominance, eventually leading to the Later Three Kingdoms and Silla's annexation by the Goryeo state. Throughout this era, each kingdom retained its unique cultural influences: Goguryeo from northern China, Baekje from southern China, and Silla from the Eurasian steppe and local traditions.^[35]

Despite their shared cultural and linguistic roots, each kingdom had distinct identities and histories. As recorded in the Book of Sui, "the customs, laws, and clothes of Goguryeo, Baekje, and Silla are generally identical".^[36] Initially rooted in shamanistic practices, they were increasingly influenced by Chinese philosophies like Confucianism and Taoism. By the 4th century, Buddhism had spread across the peninsula, briefly becoming the predominant religion of all three kingdoms. Only during the Goryeo dynasty was a collective history of the Korean Peninsula compiled.^[37]

Silla, also known as Shilla, was one of the ancient Korean kingdoms that existed from 57 BCE to 935 CE, primarily located in the southern and central parts of the Korean Peninsula. Together with Baekje and Goguryeo, they formed the historical Three Kingdoms of Korea. Of these, Silla had the smallest population, approximately 850,000 people, which was notably less than Baekje's 3,800,000 and Goguryeo's 3,500,000.^[38] Founded by Hyeokgeose of Silla from the Park family, the kingdom saw dominance by the Gyeongju Kim clan for 586 years, the Miryang Park clan for 232 years, and the Wolseong Seok clan for 172 years. Silla initially began as a part of the Samhan confederacies and later allied with China's Sui and Tang dynasties. It eventually unified the Korean Peninsula by conquering Baekje in 660 and Goguryeo in 668. Following this, Unified Silla governed most of the peninsula, while the north saw the emergence of Balhae, a successor-state of Goguryeo. After a millennium, Silla divided into the Later Three Kingdoms, which later transitioned power to Goryeo in 935.^[39]

The early history of Silla traces back to the Proto–Three Kingdoms period, during which Korea was divided into three confederacies named Samhan. Silla originated as "Saro-guk", a state within the 12-member confederacy called Jinhan. Over time, Saro-guk evolved into the Six Clans of Jinhan from the legacy of Gojoseon.^[40] Korean historical records, particularly the legend around the founding of Silla, tell of Bak Hyeokgeose founding the kingdom around present-day Gyeongju in 57 BCE. An interesting lore recounts Hyeokgeose being born from an egg laid by a white horse and being crowned king at the age of 13. There are inscriptions suggesting the royal lineage of Silla had links to the Xiongnu through a prince named Kim Il-je, or Jin Midi in Chinese sources.^[41] Some historians speculate that this tribe might have been of Korean origin and had joined the Xiongnu confederation, later returning to Korea and merging with the Silla royal family.

Silla's society, particularly after it became a centralized state, was distinctly aristocratic. The Silla royalty operated a bone rank system, determining one's social status, privileges, and even official positions. Two primary classes of royalty existed: "sacred bone" and "true bone". This bifurcation ended with the reign of Queen Jindeok, the last "sacred bone" ruler, in 654.^[42] While the king or queen was theoretically an absolute monarch, aristocrats held significant influence, with the "Hwabaek" serving as a royal council making crucial decisions, like choosing state religions.^[43] Following the unification, Silla's governance took inspiration from Chinese bureaucratic models. This was a shift from earlier times when the Silla monarchs heavily emphasized Buddhism and portrayed themselves as "Buddha-kings".

Silla's early military structure revolved around royal guards, who protected the royalty and nobility. Due to external threats, especially from Baekje, Goguryeo, and Yamato Japan, Silla developed local garrisons in each district. Over time, these garrisons evolved, leading to the formation of the "sworn banner" units. Hwarang, equivalent to Western knights, emerged as significant military leaders and played pivotal roles in Silla's conquests, particularly the unification of the Korean Peninsula. Silla's military technology, including the Cheonbono crossbows, was renowned for its efficiency and durability. Additionally, the Nine Legions, Silla's central army, consisted of diverse groups from Silla, Goguryeo, Baekje, and Mohe.^[44] Silla's maritime capabilities were also noteworthy, with the navy backing its strong shipbuilding and seamanship.

A significant part of Silla's cultural heritage resides in Gyeongju, with numerous Silla tombs still intact. Silla's cultural artifacts, particularly gold crowns and jewelry, offer insights into the kingdom's artistry and craftsmanship. A key architectural marvel is the Cheomseongdae, the oldest surviving astronomical observatory in East Asia. Internationally, Silla established relations via the Silk Road, with records of Silla found in Persian epic poems like the Kushnameh. Traders and merchants facilitated the flow of cultural and commercial items between Silla and other parts of Asia, particularly Persia.^[45] The Japanese texts, Nihon Shoki and Kojiki, also make references to Silla, recounting legends and historical ties between the two regions.

Goguryeo, also known as Goryeo, was a Korean kingdom that existed from 37 BCE to 668 CE. Situated in the northern and central parts of the Korean Peninsula, it extended its influence into modern-day Northeast China, eastern Mongolia, Inner Mongolia, and parts of Russia. As one of the Three Kingdoms of Korea, along with Baekje and Silla, Goguryeo played a crucial role in the power dynamics of the Korean peninsula and had significant interactions with neighboring states in China and Japan. The Samguk sagi, a historical record from the 12th century, states that Goguryeo was founded in 37 BCE by Jumong, a prince from Buyeo. The name "Goryeo" was adopted as the official name in the 5th century and is the origin of the modern English term "Korea".

Goguryeo's early governance was characterized by a federation of five tribes, which evolved into districts with increasing centralization. By the 4th century, the kingdom had established a regional administration system centered around fortresses. As Goguryeo expanded, it developed the gun system, a form of county-based administration. The system further subdivided regions into seong (fortresses) or chon (villages), with a susa or other officials overseeing the county.

Militarily, Goguryeo was a force to be reckoned with in East Asia. The state had a highly organized army, capable of mobilizing up to 300,000 troops at its zenith. The military structure evolved over time, with reforms in the 4th century leading to significant territorial conquests. Every male citizen was required to serve in the military, with alternatives like paying additional grain tax. The kingdom's militaristic prowess was evident in its numerous tombs and artifacts, many of which had murals showcasing Goguryeo's warfare, ceremonies, and architecture.

Goguryeo's inhabitants had a vibrant lifestyle, with murals and artifacts depicting them in predecessors of the modern hanbok. They engaged in activities such as drinking, singing, dancing, and wrestling. The Dongmaeng Festival, held every October, was a significant event where rites were performed for ancestors and gods. Hunting was also a popular pastime, especially among males, serving both as entertainment and military training. Archery contests were common, highlighting the importance of this skill in Goguryeo society.

Religiously, Goguryeo was diverse. The people worshipped their ancestors and revered mythical beasts. Buddhism was introduced to Goguryeo in 372 and became an influential religion, with many monasteries and shrines built during the kingdom's reign. Shamanism was also an integral part of Goguryeo's culture. The cultural legacies of Goguryeo, including its art, dance, and architectural innovations like ondol (floor heating system), have persisted and can still be seen in modern Korean culture.

Baekje, also known as Paekche, was a prominent kingdom in the southwestern part of the Korean Peninsula, with a rich history spanning from 18 BCE to 660 CE. It was one of the Three Kingdoms of Korea, along with Goguryeo and Silla. The kingdom was established by Onjo, the third son of Goguryeo’s founder Jumong and his consort Soseono, at Wiryeseong, which is presently a part of southern Seoul. Baekje is considered a successor to Buyeo, a state located in present-day Manchuria. The kingdom played a vital role in the historical context of the region, frequently engaging in military and political alliances and conflicts with its neighboring kingdoms, Goguryeo and Silla.

At the peak of its power during the 4th century, Baekje had expanded its territory significantly, controlling a large portion of the western Korean Peninsula and potentially even parts of China, reaching as far north as Pyongyang. The kingdom was strategically situated, allowing it to become a major maritime power in East Asia. Baekje established extensive political and trade relations with the kingdoms in China and Japan. Its maritime capabilities not only facilitated trade but also helped in spreading cultural and technological innovations across the region.

Baekje was known for its cultural sophistication and its pivotal role in the dissemination of Buddhism throughout East Asia. The kingdom embraced Buddhism in the 4th century, which led to a flourishing of Buddhist culture and arts. Baekje played a crucial role in introducing Buddhism to Japan, significantly influencing Japanese culture and religion. The kingdom was also known for its advancements in technology, art, and architecture, making substantial contributions to the cultural heritage of Korea.

However, Baekje’s prosperity did not last indefinitely. The kingdom faced constant military threats from its neighboring kingdoms and external forces. In the mid-7th century, Baekje found itself under attack from a coalition of the Tang dynasty and Silla. Despite fierce resistance, Baekje was eventually conquered in 660 CE, marking the end of its independent existence. The fall of Baekje was a significant event in the history of the Three Kingdoms of Korea, leading to a period of political restructuring in the region.

The legacy of Baekje endures to this day, with the kingdom being remembered for its cultural achievements, its role in the spread of Buddhism, and its unique position in the history of East Asia. The historical sites associated with Baekje, including its palaces, tombs, and fortresses, continue to be of great interest to historians, researchers, and tourists, shedding light on the rich history and culture of this ancient kingdom.

Gaya, a Korean confederacy existing during CE 42–532, was situated in the Nakdong River basin of southern Korea, emerging from the Byeonhan confederacy of the Samhan period. This confederation was comprised of small city-states, and it was annexed by the Silla kingdom, one of the Three Kingdoms of Korea. Archaeological evidence from the third and fourth centuries indicates a transition from the Byeonhan confederacy to the Gaya confederacy, with notable changes in military activity and funerary customs. Significant archeological sites include the Daeseong-dong and Bokcheon-dong mounded burial cemeteries, interpreted as royal burial grounds of Gaya polities.^[46]

Legend, as recorded in the 13th-century Samguk Yusa, narrates the founding of Gaya. It tells of six eggs descending from heaven in CE 42, from which six boys were born and rapidly matured. One of them, Suro, became the king of Geumgwan Gaya, while the others founded the remaining five Gayas. The Gaya polities evolved from the Byeonhan confederacy's twelve tribes, transitioning to a more militaristic ideology in the late 3rd century, influenced by elements from the Buyeo kingdom.^[47]

Gaya experienced external pressures and internal changes during its existence. Following the Eight Port Kingdoms War (209–212) between Silla and Gaya, the Gaya Confederacy managed to maintain its independence despite Silla’s growing influence, by diplomatically leveraging the influences of Japan and Baekje. However, Gaya’s independence began to wane under pressure from Goguryeo (391–412), and it was fully annexed by Silla in 562 after assisting Baekje in a war against Silla. Noteworthy is the Ara Gaya's diplomatic efforts, including hosting the Anra Conference, in a bid to maintain independence and elevate its international status.^[48]

The Gaya economy was diverse, relying on agriculture, fishing, metal casting, and long-distance trade, with a particular renown in iron-working. This expertise in iron production facilitated trade relationships with Baekje and the Kingdom of Wa, to whom Gaya exported iron ore, armor, and weaponry. Unlike Byeonhan, Gaya sought to maintain strong political ties with these kingdoms. Politically, the Gaya Confederacy maintained good relations with Japan and Baekje, often forming alliances against their common enemies, Silla and Goguryeo. The Gaya polities formed a confederacy centered around Geumgwan Gaya in the 2nd and 3rd centuries, which was later revived around Daegaya in the 5th and 6th centuries, although it ultimately fell to Silla's expansion.^[49]

Post-annexation, the Gaya elite were integrated into Silla's societal structure, including its bone-rank system. This integration is exemplified by the Sillan General Kim Yu-sin, a descendant of Gaya's royal lineage, who played a pivotal role in the unification of the Three Kingdoms of Korea. Kim's high-ranking position in Silla's hierarchy underscores the integration and influence of Gaya’s nobility within the Silla kingdom, even after the fall of the Gaya Confederacy.^[50]

In Korea, papermaking started not long after its birth in China between the 3rd and the end of the 6th century, initially using crude materials such as hemp and ramie scraps. The Three Kingdoms period (57 BCE–668 CE) saw each kingdom recording their official histories on paper, with significant advancements made in paper and ink production. The world's oldest surviving wood block print, the Pure Light Dharani Sutra, printed onto hanji around 704, stands as a testament to the sophistication of Korean papermaking during this era. Paper crafts flourished, and the Silla Kingdom, in particular, deeply integrated papermaking into Korean culture, referring to it as Gyerimji.

The Goryeo period (918–1392) marked the golden age of hanji, with a substantial increase in the quality and use of hanji, particularly in printmaking. Hanji was used for various purposes including money, Buddhist texts, medical books, and historical records. The government’s support for dak cultivation led to its widespread planting, enhancing hanji’s reputation for strength and luster across Asia. Noteworthy achievements of this period include the carving of the Tripitaka Koreana and the printing of Jikji in 1377, the world's oldest extant book printed using metal movable type.

The Joseon period (1392–1910) saw the continued proliferation of hanji in daily life, with its use extending to books, household items, fans, and tobacco pouches. Innovations included colored paper and paper made from a variety of fibers. The government established an administrative agency for paper production and even used paper armor for troops. However, the introduction of Western paper mass production methods in 1884 marked a significant shift, posing challenges to the traditional hanji industry.

Buddhism's journey to Korea began centuries after its origin in India. Through the Silk Road, Mahayana Buddhism reached China in the 1st century CE and subsequently entered Korea in the 4th century during the Three Kingdoms Period, eventually being transmitted to Japan. In Korea, Buddhism was adopted as the state religion by the Three Kingdoms: Goguryeo in 372 CE, Silla in 528 CE, and Baekje in 552 CE.^[51] Shamanism, the indigenous religion of Korea, coexisted harmoniously with Buddhism, allowing its teachings to be incorporated. Three pivotal monks instrumental in introducing Buddhism to Korea were Malananta, who brought it to Baekje in 384 CE; Sundo, who introduced it to Goguryeo in 372 CE; and Ado, who brought it to Silla.^[52]

During its early years in Korea, Buddhism was widely accepted and even became the state ideology during the Goryeo period (918–1392 CE). However, its influence waned during the Joseon era (1392–1897 CE), which spanned over five centuries, as Neo-Confucianism emerged as the dominant philosophy. It was only when Buddhist monks played a crucial role in repelling the Japanese invasions of Korea between 1592–98 that the persecution against them ceased. Nonetheless, Buddhism remained relatively subdued until the end of the Joseon period.

Post the Joseon era, the role of Buddhism in Korea experienced a resurgence, particularly during the colonial period from 1910 to 1945. Buddhist monks not only contributed to the end of Japanese rule in 1945 but also embarked on significant reforms of their traditions and practices, emphasizing a unique religious identity. This period saw the rise of the Mingung Pulgyo ideology, or "Buddhism for the people", which was centered around addressing the daily issues of the common man.^[53] After World War II, the Seon school of Korean Buddhism regained its prominence and acceptance in Korean society.

The Bone-Rank System in the ancient Korean kingdom of Silla was a hereditary caste system used to segregate society, particularly the aristocracy, based on their proximity to the throne and level of authority. This system was likely influenced by administrative laws from China, instituted by King Beopheung in 520. The Samguk Sagi, a 12th-century Korean historical text, provides a detailed account of this system, including its influence on aspects of life such as official status, marriage rights, clothing, and living conditions, though its depiction of Silla society has been criticized for being excessively static.^[54]

The highest rank in the Bone-Rank System was the "sacred bone" (Seonggol), followed by the "true bone" (Jingol), with the king after Muyeol of Silla belonging to the latter category, marking a shift in the royal lineage for over 281 years until Silla's demise.^[55] Below the "true bone" were the head ranks, with only the 6th, 5th, and 4th ranks attested, and the origins and definitions of these lower ranks remaining a topic of scholarly debate. Members of the head rank six could attain significant positions within the administrative system, while those in ranks four and five were limited to minor posts. The rigidity of the Bone-Rank System, and the limitations it placed on individuals, particularly those of the head rank six class, played a significant role in the politics of late Silla, with many seeking opportunities in Confucianism or Buddhism as alternatives.

The Bone-Rank System’s rigidity contributed to the weakening of Silla towards the end of the Unified Silla period, despite other factors also being at play. Following Silla's fall, the system was completely abolished, though various caste systems persisted in Korea until the late 19th century. The frustrated ambitions of the head rank six class and their subsequent search for opportunities outside the traditional administrative system highlight the system’s restrictive nature and its impact on Korean society during this period.

The Goguryeo-Sui War, spanning from CE 598 - 614, was a series of military invasions initiated by the Sui Dynasty of China against Goguryeo, one of the Three Kingdoms of Korea. Under the leadership of Emperor Wen and later his successor, Emperor Yang, the Sui Dynasty aimed to subdue Goguryeo and assert its dominance in the region. Goguryeo, led by King Pyeongwon followed by King Yeongyang, resisted these efforts, insisting on maintaining an equal relationship with the Sui Dynasty. Initial attempts to subdue Goguryeo were met with strong resistance, including an early setback in 598 due to unfavorable weather conditions and fierce Goguryeo defense, resulting in heavy Sui losses.

The most significant campaign occurred in 612, with Emperor Yang mobilizing a massive army, reportedly over a million strong, to conquer Goguryeo. The campaign involved prolonged sieges and battles, with Goguryeo employing strategic retreats and guerrilla tactics under the command of General Eulji Mundeok. Despite initial successes in crossing the Liao River and advancing towards Goguryeo territories, the Sui forces were ultimately decimated, most notably at the Battle of Salsu River, where Goguryeo forces ambushed and inflicted severe casualties on the Sui army. Subsequent invasions in 613 and 614 saw similar patterns of Sui aggression met with staunch Goguryeo defense, leading to further Sui failures.

The Goguryeo-Sui Wars played a pivotal role in weakening the Sui Dynasty, both militarily and economically, contributing to its eventual collapse in 618 and the rise of the Tang Dynasty. The massive loss of life, depletion of resources, and loss of trust in the Sui governance fueled widespread discontent and rebellion across China. Despite the enormous scale of the invasions and the initial might of the Sui forces, Goguryeo’s resilience and strategic acumen under leaders like King Yeongyang and General Eulji Mundeok enabled them to withstand the onslaught and protect their sovereignty, marking the wars as a notable chapter in Korean history.

The Goguryeo–Tang War (645–668) was a conflict between the Goguryeo kingdom and the Tang Dynasty, marked by alliances with various states and military strategies. The initial phase of the war (645–648) saw Goguryeo successfully repelling the Tang forces. However, after Tang and Silla's joint conquest of Baekje in 660, they launched a coordinated invasion of Goguryeo in 661, only to be forced to retreat in 662. The death of Goguryeo's military dictator, Yeon Gaesomun, in 666 led to internal strife, defections, and demoralization, which played into the hands of the Tang–Silla alliance. They launched a renewed invasion in 667, and by late 668, Goguryeo succumbed to the numerically superior armies of the Tang Dynasty and Silla, marking the end of the Three Kingdoms of Korea period and setting the stage for the subsequent Silla–Tang War.^[56]

The war's onset was influenced by Silla's requests for Tang's military support against Goguryeo and their concurrent conflict with Baekje. In 641 and 642, the Goguryeo and Baekje kingdoms saw power shifts with the rise of Yeon Gaesomun and King Uija, respectively, leading to increased hostilities and a mutual alliance against Tang and Silla. Emperor Taizong of Tang initiated the first conflict in 645, deploying a substantial army and fleet, capturing several Goguryeo strongholds, but ultimately failing to take the Ansi Fortress, resulting in a Tang retreat.^[57]

In the subsequent phases of the war (654–668), under Emperor Gaozong, the Tang Dynasty formed a military alliance with Silla. Despite initial setbacks and a failed invasion in 658, the Tang-Silla alliance successfully conquered Baekje in 660. The focus then shifted to Goguryeo, with a failed invasion in 661 and a renewed attack in 667 following Yeon Gaesomun's death and the resulting Goguryeo instability. The war concluded with the fall of Pyongyang and the conquest of Goguryeo in 668, leading to the establishment of the Protectorate General to Pacify the East by the Tang Dynasty. However, logistical challenges and a strategic shift towards a more pacifist policy by Empress Wu, amidst Emperor Gaozong's failing health, ultimately set the stage for the resistance and the forthcoming conflict between Silla and Tang.^[58]

Unified Silla, also known as Late Silla, existed from 668 CE to 935 CE, marking the unification of the Korean Peninsula under the Silla kingdom. This era began after Silla formed an alliance with the Tang Dynasty, leading to the conquest of Baekje in the Baekje–Tang War and the annexation of southern Goguryeo territories following the Goguryeo–Tang War and Silla–Tang War. Despite these conquests, Unified Silla faced political turmoil and rebellion in its northern territories, remnants of Baekje and Goguryeo, leading to the Later Three Kingdoms period in the late 9th century. The capital of Unified Silla was Gyeongju, and the government employed the “Bone Clan Class” system to maintain power, with a small elite ruling over the majority of the population.

Unified Silla was culturally and economically prosperous, known for its art, culture, and maritime prowess. The kingdom dominated East Asian seas and trade routes between China, Korea, and Japan in the 8th and 9th centuries, largely due to the influence of figures like Jang Bogo. Buddhism and Confucianism were the predominant ideologies, with many Korean Buddhists gaining fame in China. The government also conducted extensive census and record-keeping, and there was a significant emphasis on astrology and technological advancement, especially in agriculture.

However, the kingdom was not without its challenges. Political instability and intrigue were constant issues, and the elite's hold on power was threatened by internal and external forces. Despite these challenges, Unified Silla maintained close ties with the Tang Dynasty, fostering cultural exchange and learning. The era came to an end in 935 CE when King Gyeongsun surrendered to Goryeo, marking the end of the Silla dynasty and the beginning of the Goryeo period.

Balhae was a multi-ethnic kingdom whose land extends to what is now today Northeast China, the Korean Peninsula and the Russian Far East. It was established in 698 by Dae Joyeong (Da Zuorong) and originally known as the Kingdom of Jin (Zhen) until 713 when its name was changed to Balhae.

Balhae's early history involved a rocky relationship with the Tang dynasty that saw military and political conflict, but by the end of the 8th century the relationship had become cordial and friendly. The Tang dynasty would eventually recognize Balhae as the "Prosperous Country of the East". Numerous cultural and political exchanges were made. Balhae was conquered by the Khitan-led Liao dynasty in 926. Balhae survived as a distinct population group for another three centuries in the Liao and Jin dynasties before disappearing under Mongol rule.

The history of the founding of the state, its ethnic composition, the nationality of the ruling dynasty, the reading of their names, and its borders are the subject of a historiographical dispute between Korea, China and Russia. Historical sources from both China and Korea have described Balhae's founder, Dae Joyeong, as related to the Mohe people and Goguryeo.

The first national examinations were administered in the kingdom of Silla beginning in 788, after the Confucian scholar Choe Chiwon submitted the Ten Urgent Points of Reform to Queen Jinseong, the ruler of Silla at the time. However, due to Silla's entrenched bone rank system, which dictated that appointments be made on the basis of birth, these examinations did not have a strong effect on the government.

The Later Three Kingdoms period in Korea (889–936 CE) marked a tumultuous era when the once-unified Silla kingdom (668–935 CE) faced decline due to its rigid bone rank system and internal dissent, leading to the rise of regional warlords and widespread banditry. This power vacuum set the stage for the emergence of the Later Three Kingdoms, as opportunistic leaders like Gyeon Hwon and Gung Ye carved out their own states from the remnants of Silla. Gyeon Hwon revived the ancient Baekje in the southwest by 900 CE, while Gung Ye formed Later Goguryeo in the north by 901 CE, showcasing the fragmentation and the struggle for supremacy on the Korean peninsula.

Gung Ye's tyrannical rule and self-proclamation as the Maitreya Buddha led to his downfall and assassination in 918 CE, making way for his minister Wang Geon to take over and establish the Goryeo state. Meanwhile, Gyeon Hwon faced internal strife within his Baekje revival, eventually being overthrown by his son. Amidst the chaos, Silla, the weakest link, sought alliances and faced invasions, notably the sacking of its capital, Gyeongju, in 927 CE. Gyeongae of Silla's subsequent suicide and the installment of a puppet ruler only deepened Silla's crisis.

The unification of Korea was finally achieved under Wang Geon, who took advantage of the disarray within the Baekje and Goguryeo territories. After significant military victories and the voluntary surrender of Silla's last ruler Gyeongsun in 935 CE, Wang consolidated his control. His victory over the Baekje civil war in 936 CE led to the establishment of the Goryeo dynasty, which would preside over Korea for over five centuries, setting the foundation for the modern nation and its name.

Founded in 918 during the Later Three Kingdoms period, Goryeo unified the Korean Peninsula until 1392, a feat celebrated as a "true national unification" by Korean historians. This unification was significant as it merged the identities of the earlier Three Kingdoms and incorporated elements from the ruling class of Balhae, a successor of Goguryeo. The name "Korea" itself originates from "Goryeo," a testament to the dynasty's lasting influence on Korean national identity. Goryeo is acknowledged as the legitimate successor to both Later Goguryeo and the ancient Goguryeo kingdom, thereby shaping the course of Korean history and culture.

The Goryeo era, coexisting with Unified Silla, is known as the "Golden Age of Buddhism" in Korea, with the state religion reaching unprecedented heights. By the 11th century, the capital boasted 70 temples, reflecting Buddhism's deep-rooted influence in the kingdom. This period also saw a thriving commerce, with trade networks extending to the Middle East, and the capital city in modern-day Kaesong blossoming into a hub of trade and industry. The cultural landscape of Goryeo was marked by significant achievements in Korean art and culture, enriching the heritage of the nation.

Militarily, Goryeo was formidable, engaging in conflicts with northern empires such as the Liao (Khitans) and Jin (Jurchens) and challenging the Mongol-Yuan dynasty as it waned. These efforts were part of Goryeo's Northern Expansion Doctrine, aiming to reclaim lands of their Goguryeo predecessors. Despite its cultural refinement, Goryeo was able to assemble powerful military forces to resist threats like the Red Turban Rebels and Japanese pirates. However, this resilient dynasty met its end when a planned assault on the Ming dynasty sparked a coup led by General Yi Seong-gye in 1392, concluding the Goryeo chapter in Korean history.

Established in 992 under King Seongjong, the Gukjagam was the pinnacle of the Goryeo dynasty’s educational system, located in the capital, Gaegyeong. Renamed throughout its history, it was initially called Gukhak and later Seonggyungwan, reflecting its evolution as a center for advanced learning in the Chinese classics. This institution was a key component of Seongjong’s Confucian reforms, which also included the gwageo civil service examinations and the founding of provincial schools, known as hyanggyo. An Hyang, a prominent Neo-Confucian scholar, reinforced the importance of the Gukjagam during his reform efforts in the later years of Goryeo.

The curriculum at Gukjagam was initially divided into six courses, with three dedicated to the children of high-ranking officials—Gukjahak, Taehak, and Samunhak—covering the Confucian classics over nine years. The other three divisions, Seohak, Sanhak, and Yulhak, required six years to complete and were available to children of officials from lower ranks, blending technical training with classical education. In 1104, a military course called Gangyejae was introduced, marking the first formal military education in Korean history, though it was short-lived due to aristocratic-military tensions and removed in 1133.

Financial support for the Gukjagam was substantial; Seongjong’s decree in 992 provided lands and slaves to sustain the institution. Despite this, tuition costs were high, generally limiting access to the wealthy until 1304, when An Hyang instituted a tax on officials to subsidize student tuition, making education more accessible. As for its name, it was changed to Gukhak in 1275, then to Seonggyungam in 1298, and to Seonggyungwan in 1308. It briefly returned to Gukjagam during King Gongmin’s rule in 1358 before finally settling on Seonggyungwan in 1362 until the end of the Goryeo dynasty.

The Goryeo–Khitan War, fought between the Goryeo dynasty of Korea and the Khitan-led Liao dynasty of China, involved several conflicts across the 10th and 11th centuries near today's China-North Korea border. The backdrop of these wars is rooted in the earlier territorial changes following the fall of Goguryeo in 668, with subsequent shifts in power as the Göktürks were ousted by the Tang dynasty, the rise of the Uyghurs, and the emergence of the Khitan people who founded the Liao dynasty in 916. As the Tang dynasty fell, the Khitan grew stronger, and relations between Goryeo and Khitan soured, particularly after the Khitan conquest of Balhae in 926 and Goryeo's subsequent northern expansion policies under King Taejo.

Initial interactions between Goryeo and the Liao dynasty were somewhat cordial, with exchanges of gifts. However, by 993, tensions escalated into open conflict when the Liao invaded Goryeo, claiming a force of 800,000. A military stalemate led to negotiations and an uneasy peace was established, with Goryeo severing ties with the Song dynasty, paying tribute to the Liao, and expanding its territory northward to the Yalu River after expelling Jurchen tribes. Despite this, Goryeo maintained communications with the Song dynasty and fortified its northern territories. Subsequent invasions by the Liao in 1010, led by Emperor Shengzong, resulted in the sacking of the Goryeo capital and continuous hostilities, despite the inability of the Liao to maintain a significant presence in Goryeo lands.

The third major invasion in 1018 marked a turning point when General Kang Kamch'an of Goryeo employed a strategic dam release to ambush and inflict heavy casualties on Liao forces, culminating in the significant Battle of Gwiju where Liao troops were nearly annihilated. The persistent conflict and the devastating losses incurred by the Liao during this invasion eventually led both states to sign a peace treaty in 1022, concluding the Goryeo–Khitan War and stabilizing the region for a period.

Cheolli Jangseong (lit. "Thousand Li Wall") in Korean history usually refers to the 11th-century northern defense structure built during the Goryeo dynasty in present-day North Korea, though it also refers to a 7th-century network of military garrisons in present-day Northeast China, built by Goguryeo, one of the Three Kingdoms of Korea.

Samguk Sagi is a historical record of the Three Kingdoms of Korea: Goguryeo, Baekje and Silla. The Samguk Sagi is written in Classical Chinese, the written language of the literati of ancient Korea, and its compilation was ordered by King Injong of Goryeo (r. 1122-1146) and undertaken by the government official and historian Kim Busik and a team of junior scholars. Completed in 1145, it is well known in Korea as the oldest surviving chronicle of Korean history. The document has been digitized by the National Institute of Korean History and available online with Modern Korean translation in Hangul and original text in Classical Chinese.

The Goryeo military regime began with a coup in 1170, led by General Jeong Jung-bu and his associates, which marked the end of the civilian officials' dominance in the Goryeo dynasty's central government. This event did not happen in isolation; it was influenced by internal strife and external threats that had been taxing the kingdom for years. The military had grown in power due to the ongoing wars, particularly the conflicts with the Jurchen tribes to the north and the Khitan-led Liao dynasty.

Choe Chung-heon's seizure of power in 1197 further solidified military rule. The military regime existed against a backdrop of multiple invasions from the Mongol Empire, which began in the early 13th century. The prolonged Mongol invasions, which started in 1231, were a significant external factor that both justified the military's control and challenged its authority. Despite initial resistance, the Goryeo dynasty became a semi-autonomous vassal state of the Mongol Yuan dynasty, with the military leaders engaging in a complex relationship with the Mongols to retain their power.

Throughout the military regime, the Goryeo court remained a place of intrigue and shifting alliances, with the Choe family maintaining their hold on power through political maneuvering and strategic marriages until their overthrow by the military commander Kim Jun in 1258. The military regime's waning influence towards the end of the 13th century and internal power struggles set the stage for the eventual rise of General Yi Seong-gye, who would later establish the Joseon dynasty in 1392. This transition was also marked by the waning influence of the Mongol Yuan dynasty in China and the rise of the Ming dynasty, which changed the geopolitical landscape of East Asia. The fall of the military regime ended an era where military might often overruled the civil authority, and it opened the way for the Joseon dynasty's more Confucian-based governance system.

Between 1231 and 1270, the Mongol Empire conducted a series of seven major campaigns against the Goryeo dynasty in Korea. These campaigns had a devastating impact on civilian lives and resulted in Goryeo becoming a vassal state of the Yuan dynasty for approximately 80 years. The Mongols initially invaded in 1231 under Ögedei Khan's orders, leading to the surrender of Goryeo's capital, Gaesong, and demanding significant tributes and resources, including otter skins, horses, silk, clothing, and even children and craftsmen as slaves. Goryeo was forced to sue for peace, and the Mongols withdrew but stationed officials in northwestern Goryeo to enforce their terms.

The second invasion in 1232 saw Goryeo move its capital to Ganghwado and build strong defenses, exploiting the Mongols' fear of the sea. Although the Mongols occupied parts of northern Korea, they failed to capture Ganghwa Island and were repelled in Gwangju. The third invasion, lasting from 1235 to 1239, involved Mongol campaigns that ravaged parts of Gyeongsang and Jeolla Provinces. Goryeo resisted fiercely, but the Mongols resorted to burning farmland to starve the populace. Eventually, Goryeo sued for peace again, sending hostages and agreeing to the Mongols' terms. Subsequent campaigns followed, but the ninth invasion in 1257 marked the beginning of negotiations and a peace treaty.

In the aftermath, much of Goryeo was devastated, with cultural destruction and significant losses. Goryeo remained a vassal state and compulsory ally of the Yuan dynasty for about 80 years, with internal struggles continuing within the royal court. The Mongol domination facilitated cultural exchange, including the transmission of Korean ideas and technology. Goryeo gradually regained some northern territories in the 1350s as the Yuan dynasty weakened due to rebellions in China.

In 1234 the first books known to have been printed in metallic type set were published in Goryeo Dynasty Korea. They form a set of ritual books, Sangjeong Gogeum Yemun, compiled by Choe Yun-ui. While these books have not survived, the oldest book existing in the world printed in metallic movable types is Jikji, printed in Korea in 1377. The Asian Reading Room of the Library of Congress in Washington, D.C. displays examples of this metal type. Commenting on the invention of metallic types by Koreans, French scholar Henri-Jean Martin described this as "remely similar] to Gutenberg's". However, Korean movable metal type printing differed from European printing in the materials used for the type, punch, matrix, mould and in method of making an impression.

A "Confucian prohibition on the commercialization of printing" also obstructed the proliferation of movable type, restricting the distribution of books produced using the new method to the government. The technique was restricted to use by the royal foundry for official state publications only, where the focus was on reprinting Chinese classics lost in 1126 when Korea's libraries and palaces had perished in a conflict between dynasties.

During the period of Goryeo under Mongol rule, which lasted from about 1270 to 1356, the Korean Peninsula was effectively under the dominion of the Mongol Empire and the Mongol-led Yuan dynasty. This era began with the Mongol invasions of Korea, which included six major campaigns between 1231 and 1259. These invasions resulted in the annexation of northern Korean territories by the Mongols, who established Ssangseong Prefecture and Dongnyeong Prefecture.

Following the invasions, Goryeo became a semi-autonomous vassal state and a compulsory ally of the Yuan dynasty. Members of the Goryeo royal family were married to spouses from the Yuan imperial clan, solidifying their status as imperial sons-in-law. Goryeo's rulers were allowed to govern as vassals, and the Yuan established the Branch Secretariat for Eastern Campaigns in Korea to oversee Mongol supervision and political power in the region.

Throughout this period, intermarriage between Koreans and Mongols was encouraged, leading to a close relationship between the two dynasties. Korean women entered the Mongol Empire as war booty, and Korean elites were married to Mongol princesses. Goryeo's kings held a unique status within the Mongol imperial hierarchy, akin to other important families of conquered or client states.

The Branch Secretariat for Eastern Campaigns played a significant role in administering Goryeo and maintaining Mongol control. While Goryeo retained some autonomy in conducting its own government, the Branch Secretariat ensured Mongol influence in various aspects of Korean governance, including the imperial exams.

Over time, Goryeo's relationship with the Yuan dynasty evolved. King Gongmin of Goryeo began to push back against Mongol garrisons in the 1350s, coinciding with the decline of the Yuan dynasty in China. Ultimately, Goryeo severed its ties with the Mongols in 1392, leading to the establishment of the Joseon dynasty.

Under Mongol rule, the northern defenses of Goryeo were weakened, and the standing army was abolished. The Mongol military system, known as the tumen, was introduced to Goryeo, with Goryeo soldiers and officers leading these units. Korean culture also experienced significant influence from Mongol customs, including clothing, hairstyles, cuisine, and language. Economically, Yuan paper currency entered Goryeo's markets, leading to inflationary pressure. Trade routes connected Goryeo to the Yuan capital, Khanbaliq, facilitating the exchange of goods and currency.

Joseon was founded by Yi Seong-gye in July 1392, following the overthrow of the Goryeo dynasty, and lasted until it was replaced by the Korean Empire in October 1897. Initially established in what is today Kaesong, the kingdom soon moved its capital to modern-day Seoul. Joseon expanded its territory to include the northernmost regions up to the Amnok (Yalu) and Tumen rivers through the subjugation of the Jurchens, solidifying its control over the Korean Peninsula.

Throughout its five centuries, Joseon was characterized by the promotion of Confucianism as the state ideology, which significantly shaped Korean society. This period marked a decline for Buddhism, which saw occasional persecutions. Despite internal challenges and foreign threats, including devastating Japanese invasions in the 1590s and invasions by the Later Jin and Qing dynasties in 1627 and 1636–1637, Joseon was a time of cultural flourishing, marked by advances in literature, trade, and science.

The legacy of the Joseon dynasty is deeply ingrained in modern Korean culture, influencing everything from language and dialects to societal norms and bureaucratic systems. However, by the late 19th century, internal divisions, power struggles, and external pressures precipitated a rapid decline, leading to the end of the dynasty and the emergence of the Korean Empire.

Before the creation of Hangul, Koreans used Classical Chinese and various native phonetic scripts such as Idu, Hyangchal, Gugyeol, and Gakpil,^[59] which made literacy a challenge for the uneducated lower classes due to the complexity of the languages and the extensive number of Chinese characters. To address this issue, King Sejong the Great of the Joseon dynasty invented Hangul in the 15th century to promote literacy among all Koreans, regardless of social status. This new script was presented in 1446 in a document titled "Hunminjeongeum" (The Proper Sounds for the Education of the People), which laid the foundations for the script’s use.^[60]

Despite its practical design, Hangul faced opposition from the literary elite who were deeply rooted in Confucian traditions and saw the use of Chinese characters as the only legitimate form of writing. This resistance led to periods where the alphabet was suppressed, notably in 1504 by King Yeonsangun and again in 1506 by King Jungjong, which curtailed its development and standardization. However, by the late 16th century, Hangul experienced a resurgence, particularly in popular literature such as gasa and sijo poetry, and in the 17th century with the advent of Korean alphabet novels, despite the lack of orthographic standardization.^[61]

The revival and preservation of Hangul continued into the 18th and 19th centuries, garnering attention from foreign scholars such as the Dutch Isaac Titsingh who introduced a Korean book to the Western world. Hangul's integration into official documentation was realized by 1894, influenced by Korean nationalism, reform movements, and Western missionaries, marking its establishment in modern Korean literacy and education, as evidenced by its inclusion in elementary texts from 1895 and in the bilingual newspaper Tongnip Sinmun in 1896.

The Imjin War, spanning from 1592 to 1598, was initiated by Toyotomi Hideyoshi of Japan who aimed to conquer the Korean Peninsula and then China, ruled by the Joseon and Ming dynasties, respectively. The first invasion in 1592 saw the Japanese forces quickly occupy large areas of Korea but they faced staunch resistance from Ming reinforcements^[62] and attacks by the Joseon navy on their supply fleets,^[63] which forced a Japanese withdrawal from the northern provinces. Guerrilla warfare by Joseon civilian militias^[64] and supply issues led to a stalemate and an end to the first phase of the conflict in 1596, with unsuccessful peace talks ensuing.

The conflict resumed with Japan's second invasion in 1597, replicating the patterns of rapid initial territorial gains followed by a stalemate. Despite capturing several cities and fortresses, the Japanese were pushed back to the southern coasts of Korea by Ming and Joseon forces, who were then unable to dislodge the Japanese, leading to a ten-month-long deadlock.^[65] The war reached a stalemate, with neither side able to make significant progress.

The war concluded following Toyotomi Hideyoshi's death in 1598, which along with the limited territorial gains and the continued disruption of Japanese supply lines by Korean naval forces, prompted the Japanese withdrawal to Japan as ordered by the Council of Five Elders. Final peace negotiations, which took several years, ultimately resulted in normalized relations between the involved parties.^[66] The scale of the Japanese invasions, involving over 300,000 men, marked them as the largest seaborne invasions until the Normandy landings in 1944.

In the early stages of 1627, the Later Jin, under Prince Amin, launched an invasion of Joseon, which concluded after three months with the Later Jin imposing a tributary relationship over Joseon. Despite this, Joseon continued to engage with the Ming dynasty and showed resistance to the Later Jin. The invasion's backdrop involved Joseon's military support to the Ming against the Later Jin in 1619, and the political upheaval within Joseon where King Gwanghaegun was replaced by Injo in 1623, followed by the failed rebellion of Yi Gwal in 1624. The 'Westerners' faction, taking a strong pro-Ming and anti-Jurchen stance, influenced Injo to cut ties with the Later Jin, while Ming General Mao Wenlong’s military activities against the Jurchens were supported by Joseon.^[67]

The Later Jin invasion began with a 30,000 strong force led by Amin, encountering initial resistance but quickly overrunning Joseon defenses and capturing several key locations, including Pyongyang, by late January 1627. King Injo responded by fleeing Seoul and opening negotiations for peace. The subsequent treaty required Joseon to abandon the Ming era name, offer a hostage, and respect mutual territorial sovereignty. However, despite the Jin army's withdrawal to Mukden, Joseon continued to trade with the Ming and did not fully comply with the treaty's terms, leading to complaints from Hong Taiji.^[68]

The post-invasion period saw the Later Jin extracting economic concessions from Joseon to alleviate their own hardships. The uneasy relationship between the two was exacerbated when the Manchus demanded a change in diplomatic terms in 1636, which was rejected by Joseon, leading to further conflict. Ming's engagement in the conflict declined after the impeachment of General Yuan Chonghuan, and the execution of Mao Wenlong in 1629 for his unauthorized actions further strained relations, with Yuan justifying the execution as a means to reinforce imperial authority.^[69]

The Second Manchu invasion of Korea in 1636 marked a critical juncture in East Asian history, as the Qing dynasty sought to supplant the Ming dynasty's influence in the region, resulting in a direct confrontation with the Ming-aligned Joseon Korea. The invasion was precipitated by a complex interplay of escalating tensions and misunderstandings. Key events included the fierce battles and sieges, particularly the significant siege of Namhan Mountain Fortress, which culminated in the humiliating surrender of King Injo and the imposition of stringent demands on Joseon, such as the taking of royal hostages.

The invasion's aftermath had profound implications for Joseon, affecting its domestic and foreign policies. There was an overt establishment of a tributary relationship with the Qing, coupled with a covert sense of resentment and a determination to maintain the cultural legacy of the Ming dynasty. This complex sentiment led to a dual policy of official submission and private defiance. The trauma of the invasion significantly influenced Joseon's subsequent military and diplomatic efforts, including King Hyojong's ambitious but unexecuted plan to launch a northern expedition against the Qing, reflecting a lingering desire for sovereignty and autonomy.

The ramifications of the Qing conquest extended far beyond Korea's borders. The Qing's success against Joseon symbolized the dynasty's ascendancy to become the dominant power in East Asia, conclusively diminishing the Ming dynasty's hold on the region. This shift had enduring consequences, reshaping the political landscape of East Asia and setting the stage for the region's power dynamics that would persist for centuries, significantly impacting the course of Korean history and its strategic posture in the region.

The Donghak Peasant Revolution in Korea, sparked by the oppressive policies of local magistrate Jo Byeong-gap in 1892, erupted on January 11, 1894, and continued until December 25, 1895. The peasant uprising, led by followers of the Donghak movement, began in Gobu-gun and was initially spearheaded by leaders Jeon Bong-jun and Kim Gae-nam. Despite early setbacks, such as the suppression of the revolt by Yi Yong-tae and Jeon Bong-jun's temporary retreat, the rebels regrouped on Mount Paektu. They reclaimed Gobu in April, notched victories at the Battle of Hwangtojae and the Battle of the Hwangryong River, and captured Jeonju Fortress. A tenuous peace ensued following the Treaty of Jeonju in May, though the stability of the region remained precarious throughout the summer.

The Joseon government, feeling threatened by the escalating revolt, sought help from the Qing dynasty, leading to the deployment of 2,700 Qing soldiers. This intervention, contravening the Convention of Tientsin and going undisclosed to Japan, sparked the First Sino-Japanese War. This conflict significantly reduced Chinese influence in Korea and undermined China's Self-Strengthening Movement. The growing presence and influence of Japan in Korea following the war increased the anxieties of the Donghak rebels. In response, rebel leaders convened in Samrye from September to October, eventually amassing a force of 25,000 to 200,000 soldiers to attack Gongju.

The rebellion faced a major setback when the rebels suffered a crushing defeat at the Battle of Ugeumchi, followed by another defeat at the Battle of Taein. These losses marked the beginning of the end for the revolution, which saw its leaders captured and most executed by mass hanging in March 1895, as hostilities continued into the spring of that year. The Donghak Peasant Revolution, with its profound resistance against domestic tyranny and foreign intervention, ultimately reshaped Korea's socio-political landscape at the close of the 19th century.

The Korean Empire, proclaimed in October 1897 by King Gojong, marked the Joseon dynasty's transition into a modern state. This period saw the Gwangmu Reform, which aimed to modernize and westernize the military, economy, land systems, education, and industries. The empire existed until Korea's annexation by Japan in August 1910. The formation of the empire was a response to Korea's tributary relationship with China and the influence of Western ideas. Gojong's return from Russian exile led to the empire's proclamation, with the Gwangmu year as the beginning of the new era in 1897. Despite initial foreign skepticism, the declaration gradually gained implicit international recognition.

During its brief existence, the Korean Empire undertook significant reforms. The Gwangmu Reform, led by a mix of conservative and progressive officials, revived minor taxes to finance these changes, enhancing the imperial government's wealth and enabling further reforms. The army was modernized with Russian assistance until 1897, and efforts were made to establish a modern navy and promote industrialization. Land reforms aimed to better define ownership for taxation were initiated but faced internal resistance.

The Korean Empire faced diplomatic challenges, particularly from Japan. In 1904, amidst rising Japanese influence, Korea declared its neutrality, recognized by major powers. However, the 1905 Taft–Katsura Memorandum signaled U.S. acceptance of Japanese guidance over Korea. This preluded the 1905 Treaty of Portsmouth, which ended the Russo-Japanese War and confirmed Japan's influence in Korea. Emperor Gojong made desperate attempts at secret diplomacy to preserve sovereignty but faced increasing Japanese control and domestic unrest, leading to his abdication in 1907.^[70]

The ascension of Emperor Sunjong saw Japan's firmer grasp on Korea with the 1907 treaty, increasing Japanese presence in government roles. This led to the disarmament and dissolution of Korean military forces and spurred armed resistance from the righteous armies, which ultimately was suppressed by Japanese forces. By 1908, a significant percentage of the Korean officialdom was Japanese, displacing Korean officials and setting the stage for Japan's annexation of Korea in 1910.

Despite these political challenges, the Korean Empire managed economic advancements. The GDP per capita in 1900 was notably high, and the era saw the beginnings of modern Korean enterprises, some of which survive to this day. However, the economy was threatened by the influx of Japanese products and an underdeveloped banking system. Notably, figures close to the Emperor played key roles in establishing companies during this period.^[71]

During the period of Japanese rule in Korea, beginning with the Japan-Korea Annexation Treaty in 1910, the sovereignty of Korea was heavily contested. Japan claimed that the treaty was lawful, but Korea disputed its validity, asserting it was signed under duress and without the necessary consent of the Korean Emperor.^[72] The Korean resistance to Japanese rule was embodied by the formation of the Righteous Army. Despite Japan's attempts to suppress Korean culture and benefit economically from the colony, much of the infrastructure they built was later destroyed in the Korean War.^[73]

The death of Emperor Gojong in January 1919 sparked the March 1st Movement, a series of nationwide protests against Japanese rule. Spurred by Woodrow Wilson's principles of self-determination, an estimated 2 million Koreans participated, although Japanese records suggest fewer. The protests were met with brutal suppression by the Japanese, resulting in around 7,000 Korean deaths.^[74] This uprising led to the formation of the Provisional Government of the Republic of Korea in Shanghai, which is recognized in the constitution of South Korea as its legitimate government from 1919 to 1948.^[75]

Educational policies under Japanese rule were segregated by language, which affected both Japanese and Korean students. The curriculum in Korea underwent radical changes, with restrictions on the teaching of Korean language and history. By 1945, despite these challenges, the literacy rate in Korea had reached 22%.^[76] Additionally, Japanese policies enforced cultural assimilation, such as mandatory Japanese names for Koreans and the prohibition of Korean-language newspapers. Cultural artifacts were also looted, with 75,311 items taken to Japan.^[77]

The Korean Liberation Army (KLA) became a symbol of Korean resistance, consisting of exiled Koreans in China and other locations. They engaged in guerrilla warfare against Japanese forces along the Sino-Korean border and were part of allied operations in China and Southeast Asia. The KLA was supported by tens of thousands of Koreans who also joined other resistance armies like the People's Liberation Army and the National Revolutionary Army.

Upon Japan's surrender in 1945, Korea faced a significant vacuum in administrative and technical expertise. Japanese citizens, who had constituted a small percentage of the population but held significant power in urban centers and professional fields, were expelled. This left Korea's largely agrarian Korean population to rebuild and transition from decades of colonial occupation.^[78]

The Korean War, a significant conflict in the Cold War era, began on 25 June 1950 when North Korea, supported by China and the Soviet Union, launched an invasion into South Korea, backed by the United States and its UN allies. Hostilities arose from the division of Korea by occupying US and Soviet forces at the 38th parallel after Japan’s surrender on 15 August 1945, which ended its 35-year rule over Korea. By 1948, this division crystallized into two antagonistic states – the communist North Korea under Kim Il Sung and the capitalist South Korea under Syngman Rhee. Both regimes refused to recognize the border as permanent and claimed sovereignty over the entire peninsula.^[79]

Clashes along the 38th parallel and an insurgency in the South, supported by the North, set the stage for the North Korean invasion that triggered the war. The UN, lacking opposition from the USSR, which was boycotting the Security Council, responded by assembling a force from 21 countries, predominantly US troops, to support South Korea. This international effort marked the first major military action under UN auspices.^[80]

Initial North Korean advances pushed South Korean and American forces into a small defensive enclave, the Pusan Perimeter. A bold UN counteroffensive at Incheon in September 1950 turned the tide, cutting off and rolling back North Korean forces. However, the war's complexion changed when Chinese forces entered in October 1950, compelling the UN troops to retreat from North Korea. After a series of offensives and counteroffensives, the front lines stabilized near the original division at the 38th parallel.^[81]

Despite fierce fighting, the front eventually stabilized close to the original dividing line, resulting in a stalemate. On 27 July 1953, the Korean Armistice Agreement was signed, creating the DMZ to separate the two Koreas, although a formal peace treaty was never concluded. As of 2018, both Koreas have shown interest in formally ending the war, demonstrating the ongoing nature of the conflict.^[82]

The Korean War was one of the most devastating conflicts of the 20th century, with civilian casualties exceeding those of World War II and the Vietnam War, significant atrocities committed by both sides, and widespread destruction in Korea. Approximately 3 million people died in the conflict, and the bombings left North Korea extensively damaged. The war also prompted the flight of 1.5 million North Koreans, adding a significant refugee crisis to the war’s legacy.^[83]

The division of Korea into two separate entities stems from the end of World War II when Japan's surrender on 15 August 1945 led the Allied powers to consider the future of Korean self-rule. Initially, Korea was to be liberated from Japanese occupation and placed under an international trusteeship as agreed by the Allies. The division at the 38th parallel was proposed by the United States and agreed upon by the Soviet Union, intended as a temporary measure until a trusteeship could be arranged. However, the onset of the Cold War and failure in negotiations nullified any agreement on a trusteeship, leaving Korea in limbo. By 1948, separate governments were established: the Republic of Korea in the South on 15 August and the Democratic People's Republic of Korea in the North on 9 September, each backed by the United States and the Soviet Union respectively.

Tensions between the two Koreas culminated in the North's invasion of the South on 25 June 1950, initiating the Korean War which lasted until 1953. Despite immense loss and destruction, the conflict ended in a stalemate, leading to the establishment of the Korean Demilitarized Zone (DMZ), which has since remained a persistent symbol of the division between North and South Korea.

Efforts toward reconciliation and reunification have continued intermittently, with a significant breakthrough during the 2018 inter-Korean summits. On 27 April 2018, leaders from both Koreas signed the Panmunjom Declaration, agreeing on steps towards peace and reunification. Progress included the dismantling of guard posts and creation of buffer zones to reduce military tensions. In a historic move on 12 December 2018, soldiers from both sides crossed the Military Demarcation Line for the first time as a gesture of peace and cooperation.^[84]