The Manas River (Pron: ˈmʌnəs; in Bhutan Drangme Chhu; in China Niamjang) is a transboundary river in the Himalayan foothills between southern Bhutan and India. It is named after Manasa, the serpent god in Hindu mythology. It is the largest river system of Bhutan, among its four major river systems; the other three are Amo Chu or Torsa, Wong Chu or Raidak, Mo Chu or Sankosh. It is met by three other major streams before it again debouches into India in western Assam. The total length of the river is , flows through Bhutan for and then through Assam for before it joins the mighty Brahmaputra River at Jogighopa. Another major tributary of the Manas, the Aie river joins it in Assam at Bangpari.