Ataran River is a river of Burma and Thailand. In Thailand, it is usually known as the Kasat River. It merges into the larger Gyaing River and Salween River near the city of Mawlamyine. A main tributary of the Ataran River is the Zami River. The Ataran and its tributaries begin near the Thai-Burmese border and flow in a general north-north-west direction.