Moei River The Moei River forms the border between Thailand and Burma. The river is the scene of clashes between the Tatmadaw and Karen militias. Often Karen people cross the river either in order to enter Thailand as refugees or to go back to Burma. Moei River The Moei River (, , , ) is a tributary of the Salween River. Unlike most rivers in Thailand, the Moei River flows north in a northwest direction. It originates in Phop Phra District, Tak Province, flowing then from south to north across Mae Sot, Mae Ramat, and Tha Song Yang Districts, finally entering the
Salween River 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 , before re-entering Burma, passing through Karen State and Mon State. The river finally breaks out of its gorge about from the mouth, and slows down dramatically as it courses through a series of agricultural valleys. About from the mouth the river finally widens and deepens enough to become navigable for large watercraft. In quick succession it receives Dontham River from the right and Gyaing River from the left, from where the river turns