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]