The Fate of Tang Vassals Namsaeng and His Son
In 666 CE, when Namsaeng, Yeon Gaesomun's son, was on an inspection tour of the provinces, his younger brothers Namgeon and Namsan staged a coup. Namsaeng and his father, unable to return to Pyeongyang, attempted to go to Guknae Seong, but even this proved difficult. Contrary to their expectations, they did not have the unanimous support of the aristocracy in Guknae Seong. They had to find an alternative, and it was Namsaeng's son Heonseong who came up with the following plan: explain the situation to the Tang court and ask for military assistance to oust Namgeon and Namsan. Heonseong went first, and the others followed. In 668, Namsaeng led the Tang forces to his homeland and attacked Pyeongyang Seong, bringing about the demise of the Goguryeo dynasty.
Kim, Hyun-sook Research Fellow, Research Department