The earliest record of Goguryeo can be traced from the geographic monographs of the Book of Han, the name Goguryeo is attested in the name of Gaogouli County (Goguryeo County), Xuantu Commandery since 113 BCE, the year when Emperor Wu of Han China conquered Gojoseon and established the Four Commanderies. Beckwith, however, argued that the record was incorrect. Instead, he suggested that the Guguryeo people were first located in or around Liaoxi (western Liaoning and parts of Inner Mongolia) and later migrated eastward, pointing to another account in the Book of Han. The early Goguryeo tribes were under the administration of Xuantu Commandery, and were perceived as dependable clients or allies by the Han. Goguryeo leaders were conferred Han rank and status, the most prominent being the Marquis of Goguryeo, which carried a relatively independent authority within Xuantu. Some historians attribute more power to the Goguryeo during this period, linking their insurgency to the collapse of the first Xuantu Commandery in 75 BCE.

In the Old Book of Tang (945), it is recorded that Emperor Taizong refers to Goguryeo's history as being some 900 years old. According to the 12th-century Samguk sagi and the 13th-century Samgungnyusa, a prince from the Buyeo kingdom named Jumong fled after a power struggle with other princes of the court and founded Goguryeo in 37 BCE in a region called Jolbon Buyeo, usually thought to be located in the middle Yalu and Tongjia River basin, overlapping the current China-North Korea border.

Chumo was the founding monarch of the kingdom of Goguryeo, and was worshipped as a god-King by people of Goguryeo. Chumo was originally a Buyeo slang for an excellent archer, which became his name later. He was commonly recorded as Jumong by various Chinese literatures including history books written by Northern Qi and Tang—the name became dominant in future writings including Samguk Sagi and Samguk Yusa.

King Yuri was the second ruler of Goguryeo, the northernmost of the Three Kingdoms of Korea. He was the eldest son of the kingdom's founder Chumo the Holy. As with many other early Korean rulers, the events of his life are known largely from the Samguk Sagi.

Yuri is described as a powerful and militarily successful king. He conquered a Xianbei tribe in 9 BCE with the help of Bu Bun-no. In 3 BCE, Yuri moved the capital from Jolbon to Gungnae. The Han dynasty was overthrown by Wang Mang, who established the Xin dynasty. In 12 CE Wang Mang sent a messenger to Goguryeo to ask for troops to assist in the conquest of the Xiongnu. Yuri rejected the request and instead attacked Xin.He had six sons and among them were Haemyeong and Muhyul.

King Daemusin was the third ruler of Goguryeo, the northernmost of the Three Kingdoms of Korea. He led early Goguryeo through a period of massive territorial expansion, conquering several smaller nations and the powerful kingdom of Dongbuyeo.

Daemusin strengthened central rule of Goguryeo and expanded its territory. He annexed Dongbuyeo and killed its king Daeso in 22 CE. In 26 CE he conquered Gaema-guk, along the Amnok River, and later conquered Guda-guk. After fending off China's attack in 28, he sent his son, Prince Hodong, who was about 16 at the time, to attack the Nangnang Commandery. He also defeated the Nakrang Kingdom in northwestern Korea in 32. He destroyed Nangnang in 37, but an Eastern Han army sent by Emperor Guangwu of Han, captured it in 44.

King Minjung was the fourth ruler of Goguryeo, the northernmost of the Three Kingdoms of Korea. According to The History of the Three Kingdoms, he was the younger brother of the country’s third ruler, King Daemusin, and the fifth son of the second ruler, King Yuri.

During Minjung's five years of reign, he avoided military conflict and maintained peace throughout most of the kingdom. A massive pardon of prisoners occurred in his first year of reign. Several natural disasters marked his reign, including a flood during his second year of reign that occurred in the eastern provinces causing several citizens to lose their homes and starve. Seeing this, Minjung opened up the food storage and distributed food to the people.

King Taejo(dae) was the sixth monarch of Goguryeo, the northernmost of the Three Kingdoms of Korea. Under his reign, the young state expanded its territory and developed into a centrally ruled kingdom. His 93-year reign is thought to be the third longest of any monarch in the world, although this is disputed.

During the first year of his reign, he centralized the kingdom by turning the five clans into five provinces ruled by a governor from that clan, who were under the direct control of the king. He thereby firmly established royal control of the military, economy, and politics.

Upon centralizing, Goguryeo might have been unable to harness enough resources from the region to feed its population and thus, following historical pastoralist tendencies, would have sought to raid and exploit neighboring societies for their land and resources. Aggressive military activities may have also aided expansion, allowing Goguryeo to exact tribute from their tribal neighbors and dominate them politically and economically.

He fought on various occasions with China's Han Dynasty and disrupted trade between Lelang and Han. In 55, he ordered the construction of a fortress in the Liaodong Commandery. He attacked Chinese border regions in 105, 111, and 118. In 122, Taejo allied with the Mahan confederacy of central Korea and the neighboring Yemaek tribe to attack Liaodong, greatly expanding the realm of Goguryeo. He launched another major attack in 146.

King Gogukcheon of Goguryeo was the ninth monarch of Goguryeo, one of the Three Kingdoms of Korea.

In 180, Gogukcheon married Lady U, the daughter of U So of the Jena-bu, further consolidating central power. During his reign, the names of five 'bu', or powerful regional clans, become names of districts of the central kingdom, and rebellions by the aristocracy were suppressed, notably in 191.

In 184, Gogukcheon sent his younger brother, Prince Gye-su to fight Chinese Han Dynasty invasion force of the governor of Liaodong. Though Prince Gye-Su was able to block the army, the king later directly led his armies to repel Han forces in 184. In 191, King Gogukcheon adopted a meritocratic system for selecting government officials.As a result, he discovered many talented people from all over Goguryeo, the greatest of them being Eul Pa-So, who was given the position of Prime Minister.

Sima Yi's Liaodong campaign occurred in 238 CE during the Three Kingdoms period of Chinese history. Sima Yi, a general of the state of Cao Wei, led a force of 40,000 troops to attack the kingdom of Yan led by warlord Gongsun Yuan, whose clan had ruled independently from the central government for three generations in the northeastern territory of Liaodong (present-day eastern Liaoning). After a siege that lasted three months, Gongsun Yuan's headquarters fell to Sima Yi with assistance from Goguryeo (one of the Three Kingdoms of Korea), and many who served the Yan Kingdom were massacred. In addition to eliminating Wei's rival in the northeast, the acquisition of Liaodong as a result of the successful campaign allowed Wei contact with the non-Han peoples of Manchuria, the Korean Peninsula, and the Japanese archipelago. On the other hand, the war and the subsequent centralisation policies lessened the Chinese grip on the territory, which permitted a number of non-Han states to form in the area in later centuries.

The Goguryeo–Wei War was a series of invasions of the Korean kingdom of Goguryeo from 244 to 245 by the Chinese state of Cao Wei. The invasions, a retaliation against a Goguryeo raid in 242, destroyed the Goguryeo capital of Hwando, sent its king fleeing, and broke the tributary relationships between Goguryeo and the other tribes of Korea that formed much of Goguryeo's economy. Although the king evaded capture and would go on to settle in a new capital, Goguryeo was greatly diminished for a time, and would spend the next half century rebuilding its ruling structure and regaining control over its people, unmentioned by the Chinese historical texts.

Korea and its neighbours at 204 CE. © Kor Ph

By the time Goguryeo reappeared in Chinese annals, the state had evolved into a much more powerful political entity—thus the Wei invasion was identified by historians as a watershed moment in Goguryeo history that divided the different stages of Goguryeo's growth. In addition, the second campaign of the war included the furthest expedition into Manchuria by a Chinese army up to that time and was therefore instrumental in providing the earliest descriptions of the peoples who lived there.

In 259 at the King Jungcheon's 12th year of reign, the Cao Wei general Yuchi Kai (尉遲楷) invaded with his army. The king sent 5,000 cavalry to fight them in the Yangmaek region; the Wei forces were defeated and about 8,000 people slain.

In only 70 years, Goguryeo rebuilt its capital Hwando and again began to raid the Liaodong, Lelang and Xuantu commandaries. As Goguryeo extended its reach into the Liaodong Peninsula, the last Chinese commandery at Lelang was conquered and absorbed by Micheon in 313, bringing the remaining northern part of the Korean peninsula into the fold. This conquest resulted in the end of Chinese rule over territory in the northern Korean peninsula, which had spanned 400 years. From that point on, until the 7th century, territorial control of the peninsula would be contested primarily by the Three Kingdoms of Korea.

Goguryeo met major setbacks and defeats during the reign of Gogukwon in the 4th century. In the early 4th century, the nomadic proto-Mongol Xianbei people occupied northern China. During the winter of 342, the Xianbei of Former Yan, ruled by the Murong clan, attacked and destroyed Goguryeo's capital, Hwando, capturing 50,000 Goguryeo men and women to use as slave labor in addition to taking the queen mother and queen prisoner, and forced King Gogukwon to flee for a while. The Xianbei also devastated Buyeo in 346, accelerating Buyeo migration to the Korean peninsula.

King Sosurim of Goguryeo became king in 371 when his father King Gogugwon was killed by the Baekje King Geunchogo's assault on Pyongyang Castle.

Sosurim is considered to have strengthened the centralization of authority in Goguryeo, by establishing state religious institutions to transcend tribal factionalism. The development of centralized government system was largely attributed to reconciliation policy of Sosurim with its southern opponent, Baekje.

The year 372 held its critical importance in Korean history not only for Buddhism but also for Confucianism and Daoism. Sosurim also established the Confucian institutions of Taehak (태학, 太學) to educate the children of the nobility. In 373, he promulgated a code of laws called (율령, 律令) which stimulated the institutionalized law systems including penal codes and codified regional customs.

In 374, 375, and 376, he attacked the Korean kingdom of Baekje to the south, and in 378 was attacked by the Khitan from the north. Most of King Sosurim's reign and life was spent trying to keep Goguryeo under control and also strengthening royal authority. Although he was not able to avenge the death of his father and previous Goguryeo ruler, King Gogugwon, he did play a major role in setting up the foundations that made the great conquests of his nephew and later ruler of Goguryeo, King Gwanggaeto the Great achieve reckless subjugations.

In 372, King Sosurim received Buddhism through travelling monks of Former Qin and built temples to house them. It is said the king of Former Qin during Sixteen Kingdoms period sent Monk Sundo with images and scriptures of Buddha and; Monk Ado, native Goguryeo returned two years later. Under full-pledged support of royal family, it is said the first temple, Heungguk monastery of Korean kingdoms was supposedly constructed around the capital. Though there are several evidences that Buddhism was established before the year of 372 such as mid-4th century mausoleum styles under the Buddhist influence, it is well accepted that Sosurim consolidated Buddhist footprints not only on Korean people’s spiritual world but also in terms of bureaucracy systems and ideology.

The Goguryeo–Wa War occurred at the end of the 4th century and the beginning of the 5th century between Goguryeo and the Baekje–Wa alliance. As a result, Goguryeo made both Silla and Baekje its subjects, bringing about a unification of the Three Kingdoms of Korea that lasted about 50 years.

Gwanggaeto the Great was the nineteenth monarch of Goguryeo. Under Gwanggaeto, Goguryeo began a golden age, becoming a powerful empire and one of the great powers in East Asia. Gwanggaeto made enormous advances and conquests into: Western Manchuria against Khitan tribes; Inner Mongolia and the Maritime Province of Russia against numerous nations and tribes; and the Han River valley in central Korea to control over two-thirds of the Korean peninsula.

In regard to the Korean peninsula, Gwanggaeto defeated Baekje, the then most powerful of the Three Kingdoms of Korea, in 396, capturing the capital city of Wiryeseong in present-day Seoul. In 399, Silla, the southeastern kingdom of Korea, sought aid from Goguryeo due to incursions by Baekje troops and their Wa allies from the Japanese archipelago. Gwanggaeto dispatched 50,000 expeditionary troops, crushing his enemies and securing Silla as a de facto protectorate; he thus subdued the other Korean kingdoms and achieved a loose unification of the Korean peninsula under Goguryeo. In his western campaigns, he defeated the Xianbei of the Later Yan empire and conquered the Liaodong peninsula, regaining the ancient domain of Gojoseon.

Gwanggaeto's accomplishments are recorded on the Gwanggaeto Stele, erected in 414 at the supposed site of his tomb in Ji'an along the present-day China–North Korea border.

Jangsu of Goguryeo was the 20th monarch of Goguryeo, the northernmost of the Three Kingdoms of Korea. Jangsu reigned during the golden age of Goguryeo, when it was a powerful empire and one of the great powers in East Asia. He continued to build upon his father's territorial expansion through conquest, but was also known for his diplomatic abilities. Like his father, Gwanggaeto the Great, Jangsu also achieved a loose unification of the Three Kingdoms of Korea. In addition, Jangsu's long reign saw the perfecting of Goguryeo's political, economic and other institutional arrangements. During his reign, Jangsu changed the official name of Goguryeo (Koguryŏ) to the shortened Goryeo (Koryŏ), from which the name Korea originates.

In 427, he transferred the Goguryeo capital from Gungnae Fortress (present-day Ji'an on the China-North Korea border) to Pyongyang, a more suitable region to grow into a burgeoning metropolitan capital, which led Goguryeo to achieve a high level of cultural and economic prosperity.

Goguryeo reached its zenith in the 6th century. After this, however, it began a steady decline. Anjang was assassinated, and succeeded by his brother Anwon, during whose reign aristocratic factionalism increased. A political schism deepened as two factions advocated different princes for succession, until the eight-year-old Yang-won was finally crowned. But the power struggle was never resolved definitively, as renegade magistrates with private armies appointed themselves de facto rulers of their areas of control.

Taking advantage of Goguryeo's internal struggle, a nomadic group called the Tuchueh attacked Goguryeo's northern castles in the 550s and conquered some of Goguryeo's northern lands. Weakening Goguryeo even more, as civil war continued among feudal lords over royal succession, Baekje and Silla allied to attack Goguryeo from the south in 551.

The Goguryeo–Sui War were a series of invasions launched by the Sui dynasty of China against Goguryeo, one of the Three Kingdoms of Korea, between CE 598 and CE 614. It resulted in the defeat of the Sui and was one of the pivotal factors in the collapse of the dynasty, which led to its overthrow by the Tang dynasty in CE 618.

The Sui dynasty united China in CE 589, defeating the Chen dynasty and ending the division of the country that spanned almost 300 years. After the unification of China, Sui asserted its position as an overlord of neighbouring countries. However, in Goguryeo, one of the Three Kingdoms of Korea, king Pyeongwon and his successor, Yeongyang, insisted on maintaining an equal relationship with the Sui dynasty.

Emperor Wen of Sui was displeased with the challenge from Goguryeo, which continued small scale raiding into Sui's northern border. Wen sent diplomatic papers in 596 after Sui envoys spotted Goguryeo diplomats in the yurt of the Eastern Turkish Khanate and demanded the Goguryeo to cancel any military alliance with the Turks, stop the annual raiding of Sui border regions, and acknowledge Sui as their overlord. After receiving the message, Yeongyang launched a joint pre-emptive invasion with the Malgal against the Chinese along the border in present-day Hebei province in 597.

In 612, Emperor Yang of Sui invaded Goguryeo with well over one million men. Unable to overcome the stalwart Goguryeo defense at Liaoyang/Yoyang, he dispatched 300,000 troops to Pyongyang, the capital of Goguryeo.

The Sui forces were unable to advance further due to the internal discord within the Sui Dynasty command, and the lack of supplies due to the secret disposal of the soldiers' personal equipment and munitions in the middle. Goguryeo General Eulji Mundeok , who had been blocking the Sui forces for several months, noticed this. He prepared to attack the Salsu River (Cheongcheon River) and caused damage while pretending to retreat deep into Goguryeo territory. Eulji Mundeok had cut off the flow of water with a dam in advance, and when the Sui troops reached the river, the water level was shallow. When the unsuspecting Sui troops were halfway across the river, Eulji Mundeok opened the dam, causing the onslaught of water to drown thousands of enemy soldiers. The Goguryeo cavalry then charged the remaining Sui forces, inflicting enormous casualties.

The surviving Sui troops were forced to retreat at a breakneck pace to the Liaodong Peninsula to avoid being killed or captured. Many retreating soldiers died of disease or starvation as their army had exhausted their food supplies. This led to an overall campaign loss of all but 2,700 Sui troops out of 300,000 men. The Battle of Salsu is listed among the most lethal "classical formation" battles in world history.

With a victory over Sui China at the Salsu River, Goguryeo eventually won the Goguryeo–Sui War, while the Sui dynasty, crippled by the enormous loss of manpower and resources as a result of its Korean campaigns, started to crumble from within and was finally brought down by internal strife, to be replaced soon thereafter by the Tang.

In the winter of 642, King Yeongnyu was apprehensive about Yeon Gaesomun, one of the great nobles of Goguryeo, and plotted with other officials to kill him. However, Yeon Gaesomun caught news of the plot and killed Yeongnyu and 100 officials, initiating a coup d'état. He proceeded to enthrone Yeongnyu's nephew, Go Jang, as King Bojang while wielding de facto control of Goguryeo himself as the generalissimo, Yeon Gaesomun took an increasingly provocative stance against Silla Korea and Tang China. Soon, Goguryeo formed an alliance with Baekje and invaded Silla, Daeya-song (modern Hapchon) and around 40 border fortresses were conquered by the Goguryeo-Baekje alliance.

The first conflict of the Goguryeo–Tang War started when Emperor Taizong (r. 626–649) of the Tang dynasty led a military campaign against Goguryeo in 645 to protect Silla and punish Generalissimo Yeon Gaesomun for the killing of King Yeongnyu. The Tang forces were commanded by Emperor Taizong himself, generals Li Shiji, Li Daozong, and Zhangsun Wuji. In 645, after capturing multiple Goguryeo fortresses and defeating large armies in his path, Emperor Taizong appeared poised to march on the capital Pyongyang and conquer Goguryeo, but could not overcome the strong defenses at Ansi Fortress, which was commanded by Yang Manchun at the time. Emperor Taizong withdrew after more than 60 days of battle and unsuccessful siege.

Wars between Tang dynasty and kingdoms of Korean Peninsula, including Goguryeo, Silla and Baekje. © SY

The Goguryeo–Tang War occurred from 645 to 668 and was fought between Goguryeo and the Tang dynasty. During the course of the war, the two sides allied with various other states. Goguryeo successfully repulsed the invading Tang armies during the first Tang invasions of 645–648. After conquering Baekje in 660, Tang and Silla armies invaded Goguryeo from the north and south in 661, but were forced to withdraw in 662. In 666, Yeon Gaesomun died and Goguryeo became plagued by violent dissension, numerous defections, and widespread demoralization. The Tang–Silla alliance mounted a fresh invasion in the following year, aided by the defector Yeon Namsaeng. In late 668, exhausted from numerous military attacks and suffering from internal political chaos, Goguryeo and the remnants of Baekje army succumbed to the numerically superior armies of the Tang dynasty and Silla. The war marked the end of the Three Kingdoms of Korea period which had lasted since 57 BCE. It also triggered the Silla–Tang War during which the Silla Kingdom and the Tang Empire fought over the spoils they had gained.

The Siege of Ansi was a battle between Goguryeo and Tang forces in Ansi, a fortress in the Liaodong Peninsula, and the culmination of the First campaign in the Goguryeo–Tang War. The confrontation lasted for about 3 months from 20 June 645 to 18 September 645. The initial phase of combat resulted in the defeat of a Gorguryeo relief force of 150,000 and resulted in the Tang troops laying siege to the fortress. After a siege lasting around 2 months, the Tang forces constructed a rampart. However, the rampart was on the brink of completion, when a section of it collapsed and was taken over by the defenders. This, along with arriving Goguryeo reinforcements and the lack of supplies, forced Tang troops into a retreat. Over 20,000 Goguryeo troops were killed during the siege.

In 666 CE, the death of Yeon Gaesomun, a powerful leader of Goguryeo, led to internal turmoil. His eldest son, Yeon Namsaeng, succeeded him but faced rumors of conflict with his brothers, Yeon Namgeon and Yeon Namsan. This strife culminated in Yeon Namgeon's rebellion and seizure of power. Amidst these events, Yeon Namsaeng sought help from the Tang Dynasty, changing his family name to Cheon in the process. Emperor Gaozong of Tang saw this as an opportunity to intervene and launched a military campaign against Goguryeo.

In 667, Tang forces crossed the Liao River, capturing key fortresses and facing resistance from Yeon Namgeon. With the assistance of defectors, including Yeon Namsaeng, they overcame opposition at the Yalu River. By 668, Tang and allied Silla forces laid siege to Pyongyang. Yeon Namsan and King Bojang surrendered, but Yeon Namgeon resisted until betrayed by his general, Shin Seong. Despite his attempt at suicide, Yeon Namgeon was captured alive, marking the end of Goguryeo. The Tang Dynasty annexed the region, establishing the Andong Protectorate.

The downfall of Goguryeo was largely attributed to the internal conflict following Yeon Gaesomun's death, which facilitated the Tang–Silla alliance's victory. However, Tang's rule was resisted, leading to forced relocations of Goguryeo people and their inclusion in Tang society, with some like Go Sagye and his son Gao Xianzhi serving the Tang government.

Meanwhile, Silla achieved unification of most of the Korean peninsula by 668 but faced challenges due to its reliance on Tang. Despite Silla’s resistance, the Tang Dynasty maintained control over former Goguryeo territories. The Silla–Tang Wars ensued, resulting in Tang forces being expelled from areas south of the Taedong River, but Silla couldn't reclaim the northern territories.

The culture of Goguryeo was shaped by its climate, religion, and the tense society that people dealt with due to the numerous wars Goguryeo waged. Not much is known about Goguryeo culture, as many records have been lost. Goguryeo art, preserved largely in tomb paintings, is noted for the vigour and fine detail of its imagery. Many of the art pieces have an original style of painting, depicting various traditions that have continued throughout Korea's history. Cultural legacies of Goguryeo are found in modern Korean culture, for example: Korean fortress, ssireum, taekkyeon, Korean dance, ondol (Goguryeo's floor heating system) and the hanbok.

Remains of walled towns, fortresses, palaces, tombs, and artifacts have been found in North Korea and Manchuria, including ancient paintings in a Goguryeo tomb complex in Pyongyang. Some ruins are also still visible in present-day China, for example at Wunü Mountain, suspected to be the site of Jolbon fortress, near Huanren in Liaoning province on the present border with North Korea. Ji'an is also home to a large collection of Goguryeo era tombs, including what Chinese scholars consider to be the tombs of Gwanggaeto and his son Jangsu, as well as perhaps the best-known Goguryeo artifact, the Gwanggaeto Stele, which is one of the primary sources for pre-5th-century Goguryeo history.

The modern English name "Korea" derives from Goryeo (also spelled as Koryŏ) (918–1392), which regarded itself as the legitimate successor of Goguryeo. The name Goryeo was first used during the reign of Jangsu in the 5th century.