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
Peopling of Thailand through Laos. The Iu Mien arrived in Thailand approximately 200 years ago, contemporaneously with a large number of other Hmong–Mien migrants. The primary homeland of the Hmong–Mien ethnicity is said to be Kweichow, a province of southern China, where they settled at least 2,000 years ago. The Karen left Tibet and migrated to Burma as refugees, establishing themselves along the Burmese border with Thailand. When during World War II the Japanese occupied Burma, long-term tensions between the Karen and Burmese turned into open fighting. After the war ended, Burma was granted independence in January 1948, and the Karen, led by