Kao-kou-li

The journey to the monuments of the ancient Korean kingdom of Kao-kou-li (Kokurye, in Korean), in the Hsien of Chi-an, on the r. bank of the Ya-lu Chiang (Am-nok kang or Pul-ryu in Korean), can be made by either of two routes:[…]

Source: wiktionary

Ho-pei was then a prosperous and populous agricultural region and the centre of Chinese culture in the north. Moreover, there was peace and trade with its north-eastern neighbour, Kao-kou-li. After Ch’i was conquered by Chou and after Chou’s successor Sui had united the whole empire, the flow of trade from the south passed by Ho-pei to the north-west. Then Sui attacked Kao-kou-li. The reasons for the ensuing intermittent war which lasted for three-quarters of a century and proved so costly and profitless to China are obscure. It is not impossible, however, that the court at Ch’ang-an felt a danger in the existence of close relations between Ho-pei and its north-eastern neighbour. If the people of Ho-pei were indeed hostile to being ruled from the west, there might have been danger of their seeking support from Korea. However this may be, and it is largely conjecture, the state of enmity between Kao-kou-li and China must have seriously interfered with trade across southern Manchuria and have further tended to turn northern Ho-pei into an economic backwater.

Source: wiktionary

Kao-kou-li later pushed down into the Korean peninsula and became the northernmost of the Three Kingdoms among which Korea was divided in Sui and T'ang times.

Source: wiktionary

As recorded in the "History of Kao-kou-li," in Wei Shu (written 551-554), the story is as follows: "Kao-kou-li was founded by the Fu-yü, who called their ancestor Chu Meng.

Source: wiktionary