Koguryo had continually advanced to west since the founding state, and eventually ejected the Chinese commanderies named Liaodong-chun and Hsunto-chun by King Gwanggaeto in early 5th century. So Koguryo conquered all of Liaodong Territory. Yet after K...
Koguryo had continually advanced to west since the founding state, and eventually ejected the Chinese commanderies named Liaodong-chun and Hsunto-chun by King Gwanggaeto in early 5th century. So Koguryo conquered all of Liaodong Territory. Yet after Koguryo had satisfied with this strategic success, and then shifted her capital from Tung-kou(Jian) - a tributary to the Yalu River - to Pyongyang on a Southern area. Because Koguryo aimed to suppress two growing countries on the south of Korean Peninsular, Baekje and Silla.
Thereafter, Koguryo had very successfully struggled against the Chinese invaders at her western frontier beside the Liao River until her min by the attack of Tang and Silla in 668. However, in geo-political aspects, the defence of Liaodong without possession of Liaoshi Territory on the west side of Liao River was essentially impossible. It is well known story that the Kung-sun warlords were ruined by Wei(Tsao) Dynasty in early 3rd century and that the Manchurian warlord Zhang Tso-lin strived to get Jehol Province in 1920s. Koguryo kept struggling against the Chinese invaders at the many strong mountain-fortresses. However, because of this strategy for defence, Koguryo was finally ruined by the attack of Tang.