evidence: An international waterway and a major source of hydroelectric power, the Yalu River forms the boundary between North Korea and the Northeast Region (Manchuria) of China. The river is 491 miles (790 kilometers) long. It begins atop Baitou Mountain at a height of 9,000 feet (2,750 meters) above sea level, winds southward to Hyesan, North Korea, changes course to the northwest for 80 miles (130 kilometers), and then turns to flow southwestward for 200 miles (320 kilometers) to empty into Korea Bay off the Yellow Sea. Its main tributaries are the Herchun and Changjin rivers. The largest hydroelectric plant in eastern Asia is situated on the Yalu at Sup’ung-nodongjagu, North Korea. Although the river’s volume can generate 4,200,000 kilowatts of electricity, the 133-square-mile (344-square-kilometer) reservoir has a potential of 7,000,000 kilowatts. Both North Korea and China rely on the electricity it supplies for their industries and railways. [...] The Yalu is both a political boundary and a cultural dividing line. Only Koreans inhabit the southeastern side, and only Chinese live on the northwestern banks. Because of its economic value and strategic location, the river played a major political role in the Korean War from 1950 to 1953.