Capitals: Jolbon, Guangnae, Pyongyang
Official Languages: Goguryeo
Established: 37 BC/BCE
Disestablished: 668 AD/CE
In the geographic monographs of the Book of Han, the word Goguryeo made its first appearance in 113 BC in the name of Gaogouli County under the jurisdiction of Xuantu Commandery. 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 BC 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.
At its founding, the Goguryeo people are believed to be a blend of people from Buyeo and Yemaek, as leadership from Buyeo may have fled their kingdom and integrated with existing Yemaek chiefdoms. The Records of the Three Kingdoms, in the section titled "Accounts of the Eastern Barbarians", implied that Buyeo and the Yemaek people were ethnically related and spoke a similar language.
The Stele states that Jumong was the first king and ancestor of Goguryeo and that he was the son of the prince of Buyeo and daughter of Habaek, the god of the Amnok River or, according to an alternative interpretation, the sun god Haebak. The Samguk sagi and Samgungnyusa paint additional detail and names Jumong's mother as Yuhwa. Jumong's biological father was said to be a man named Haemosu who is described as a "strong man" and "a heavenly prince." The river god chased Yuhwa away to the Ubal River due to her pregnancy, where she met and became the concubine of Geumwa.
Jumong was well known for his exceptional archery skills. Eventually, Geumwa's sons became jealous of him, and Jumong was forced to leave Eastern Buyeo. The Stele and later Korean sources disagree as to which Buyeo Jumong came from. The Stele says he came from Buyeo and the Samgungnyusa and Samguk sagi say he came from Eastern Buyeo. Jumong eventually made it to Jolbon, where he married Soseono, daughter of its ruler. He subsequently became king himself, founding Goguryeo with a small group of his followers from his native country.
Goguryeo developed from a league of various Yemaek tribes to an early state and rapidly expanded its power from their original basin of control in the Hun River drainage. In the time of Taejodae in 53 AD, five local tribes were reorganized into five centrally ruled districts. Taejo conquered the Okjeo tribes of what is now northeastern Korea as well as the Dongye and other tribes in Southeastern Manchuria and Northern Korea. From the increase of resources and manpower that these subjugated tribes gave him, Taejodae led Goguryeo in attacking the Han Commanderies of Lelang and Xuantu in the Korean and Liaodong Peninsulas, becoming fully independent from them.
In the chaos following the fall of the Han Dynasty, the former Han commanderies had broken free of control and were ruled by various independent warlords. Surrounded by these commanderies, who were governed by aggressive warlords, Goguryeo moved to improve relations with the newly created dynasty of Cao Wei in China and sent tribute in 220. In 238, Goguryeo entered into a formal alliance with Wei to destroy the Liaodong commandery.
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.
In the late 6th and early 7th centuries, Goguryeo was often in military conflict with the Sui and Tang dynasties of China. Its relations with Baekje and Silla were complex and alternated between alliances and enmity. A neighbor in the northwest were the Eastern Göktürk which was a nominal ally of Goguryeo.
In 667, the Chinese army crossed the Liao River and captured Shin/Xin Fortress. The Tang forces thereafter fought off counterattacks by Yeon Namgeon, and joined forces with and received every possible assistance from the defector Yeon Namsaeng, although they were initially unable to cross the Yalu River due to resistance. In spring of 668, Li Ji turned his attention to Goguryeo's northern cities, capturing the important city of Buyeo. In fall of 668, he crossed the Yalu River and put Pyongyang under siege in concert with the Silla army. Yeon Namsan and Bojang surrendered and Goguryeo rule came to an official end.