A sharp bend west and another south takes the Salween between the great mountain ranges of eastern Burma, the Daen Lao Range, a subrange of the Shan Hills, followed by the Dawna Hills in the east and the Karen Hills in the west, Burma -Geography the river then receives the Pai River also from the left and flows through Salawin National Park to join the Moei River from the east as it approaches Thailand, where it is called the Salawin, forming the Burma-Thailand boundary for about 120 kilometers , before re-entering Burma, passing through Karen State and Mon State.