Koguryeo

Goguryeo, also spelled Koguryeo, Gaogouli, or Goguryŏ, was one of the Three Kingdoms of Korea and a major power in Northeast Asia from 37 BCE to 668 CE. It occupied large parts of the northern Korean Peninsula and southern Manchuria. The kingdom was founded by Jumong, who established his capital at Jolbon. Over the centuries the capital moved, with major seats at Gungnae Fortress, Hwando, and later Pyongyang, reflecting its expanding reach.

Goguryeo reached its height under kings such as Gwanggaeto the Great (r. 391–413) and his son Jangsu, expanding into Manchuria and northern Korea and developing a centralized aristocratic monarchy. The state built extensive fortifications and fought frequent wars with Baekje and Silla, as well as with Chinese dynasties. It played a leading role in regional power dynamics, resisting several Chinese invasions, most notably the Sui invasion in the early 7th century.

Culture and society included a strong aristocratic system, a tradition of mural tombs, and early Buddhism that began to influence the court by the 4th–5th centuries. The Goguryeo language was spoken locally, while Chinese characters were used for inscriptions and administration. The Gwanggaeto Stele, erected in 414 CE, is a key primary source on its expansion.

Fall and legacy: In 668, Tang dynasty and the kingdom of Silla conquered Goguryeo, and its core territory was absorbed into Unified Silla. Some refugees later established Balhae in Manchuria and the northern Korean Peninsula. The name Goryeo, from which the later Korean dynasty derives, is linked to Goguryeo.