The river flows in northeast Asia, on the border between China and North Korea in its upper reaches, and between North Korea and Russia in its last before entering the Sea of Japan. The river forms much of the southern border of Jilin Province in Northeast China and the northern borders of North Korea's North Hamgyong and Ryanggang provinces. Baekdu Mountain on the Chinese-North Korean border is the source of the river, as well as of the Amnok River, also called the Yalu River (which forms the western portion of the border of North Korea and China).