King Taejo was the sixth monarch of Goguryeo, who ruled the country incredibly long for 93 years. Under his rule, by the late first century, Goguryeo was able to significantly expand its territory and establish itself as a state with a systematic and centralized ruling structure.
King Taejo was the grandson of Goguryeo’s second king, Yuri, and the son of Go Jaesa, the head of the Go clan of the Gyeru lineage. Gyeru was one of the five powerful houses of the royal court. Following the assassination of the fifth king, Mobon, in the year 53, the court nominated Jaesa to be the next king, although the previous king had his own crown prince, who was eventually denied the throne. Jaesa refused the kingship, though, citing his old age, and his seven-year-old son became king instead. The queen dowager was appointed as regent to administer state affairs for the boy king. It is assumed that the queen acted as regent until the young king was around 18 or 22 years old.
After rising to the throne, King Taejo started conquering and absorbing neighboring states under his rule. He first annexed the regions of Eastern Okjeo and Eastern Ye and consistently launched massive offensives against Chinese towns and commanderies. The king fought with China’s Later Han Dynasty on various occasions. In the year 55, he ordered the construction of ten fortresses in the Liaodong Commandery to prepare against invasions of Later Han. He went as far as to attack Chinese border regions on several occasions. In the year 122, the king allied with the Mahan confederacy of central Korea and the neighboring Yemaek tribe to attack Liaodong. He launched another major attack in the year 146. As a result, King Taejo successfully advanced into Liaodong and the plains of the northern Korean Peninsula, driving Chinese forces out toward the west and greatly expanding the realm of Goguryeo. Goguryeo’s efforts toward national growth during this early period can be characterized as a series of struggles to expel Chinese forces from its area of dominance.
All this territorial expansion was a great achievement for the king. But Taejo went a step further to consolidate his ruling system domestically by centralizing sovereign power. He rearranged his state into five districts—North, South, East, West and Center, with five local clans ruling these districts. In doing so, he was able to control people in each district. Also, the king created a tributary relationship with smaller tribes. During his reign around the late first century, Goguryeo became a powerful country that controlled all the neighboring tribes under its strong leadership. The king’s posthumous title “Taejo,” which means “Great Ancestor,” reflects his remarkable accomplishments.
In the year 146, he abdicated the throne to his younger brother Suseong, who was extremely eager about royal power. Taejo lived as an ex-king until he died in the year 165 at the age of 118, after ruling for 93 years. He is recorded as the longest living and reigning king in Korean history. Some records say King Taejo actually ruled for 68 years, which is still quite a long time for any king to stay in power. The title “Taejo” is generally given to the first or second king of a dynasty. This suggests that the king contributed greatly to making Goguryeo a well functioning state.