It is joined at the lower course by a large tributary, the Xinkai River (新开河), which drains the southeast slopes of the Khingan Mountains and is dry in its upper reaches except after thunderstorms, 8 kilometers north of the city of Shuangliao, before turning southeast to join the Dongliao River to form the Liao River proper near the common border of Liaoning, Jilin and Inner Mongolia.