Koguryo claimed to be the successor to the Ko-choson (ancient) kingdom but it took almost a hundred years for it to develop an army sufficient enough to wage full-scale attacks against the entrenched Chinese. The subsequent fall of the Han Dynasty and ensuing political divisions in China enabled Koguryo to consolidate and extend its power. After a long struggle against the Chinese, by the fourth century, Koguryo had gained full control of Nang-nang, achieved undisputed control of all of Manchuria east of the Liao River as well as of the northern and central regions of the Korean Peninsula, and was attempting to spread its control over the other two kingdoms on the Korean peninsula.
Koguryo's best-known ruler, King Kwanggaet'o (whose name literally means "broad expander of territory") lived to be only thirty-nine years of age, but reigned twenty-one years, from 391 to 412AD. During that period, he conquered 65 walled cities and 1,400 villages, in addition to aiding Silla when it was attacked by the Japanese. Koguryo moved its capital to P'yongyang in 427AD and ruled the territory north of the Han River. However, Koguryo's expansion caused it to come into conflict with the Sui Dynasty of China (581-617AD) in the west and Silla, which was beginning to expand northward, in the south.
The Chronicle of Old Joseon , a history book on the old Joseon Dynasty, describes life in Koguryo. It said that people gathered on March tenth of every year at a site of a ritual where they performed a sword dance and held archery and Subak contests. The book implies that Subak was one of the popular events for rituals in Koguryo days. The chronicle said:
"At a power contest of Subak techniques, Lee Yi-Min punched a pillar of the house with his right-hand fist, then some of the props of the roof were shaken."