Within the context of the deterioration of Sino-Soviet relations, China moved to resolve its historic boundary dispute with Korea. The 800-mile border dividing China and Korea runs along the Yalu and Tumen Rivers for all but a 20-mile segment, and a few islands in these rivers remain a source of friction. The boundary is complicated by the contemporary esoteric debate over the ancient Korean kingdom of Koguryo (37 BC-668 AD) that extended into Manchuria, China’s northeastern region. Such historical issues continue to be contentious in Sino-Korean relations and overshadow the debate over historical boundaries. There are strong irredentist feelings among Chines and Koreans about the boundary, especially the status of Baekdusan/Changbaishan. Nevertheless, a boundary treaty was signed in 1970 and a maps reflecting this agreement were published starting in 1970.