《旧唐书·列传·卷三》
 辽河的东部，朝鲜的土地，《尚书·禹贡》篇把它划为距离王都最远的边缘地带，周朝的天子不把它的首领当作诸侯而当贵宾对待，只是保持联络关系，通达声威教化，如果希望爱护人民，不必要求拓展疆土。
辽水之东，朝鲜之地，《禹贡》以为荒服，周王弃而不臣，示以羁縻，达其声教，苟欲爱人，非求拓土。
To the east of the Liao River, on the land of Korea, the "Book of History·Yugong" listed it as the farthest edge of the king's capital. The emperor of the Zhou Dynasty did not treat its leader as a vassal but as a VIP, just to maintain contact, spread prestige and education, and if one wished to protect the people, it was not necessary to expand the territory.