The Nen River or Nenjiang (Chinese: 嫩江; pinyin: Nèn Jiāng; Wade–Giles: Nen-chiang), or Nonni (Manchu: ᠨᠣᠨ ᡠᠯᠠ, Möllendorff: non ula, Abkai: non ula) is a river in Northeast China. The Nen River flows through the northern part of Heilongjiang Province and the northeastern section of Inner Mongolia, some parts of the river forming the border between the two regions. At 1,370 km (850 mi) in length, the Nen River is the longest tributary of the Songhua River. The Nen River flows in the general southern direction in a wide valley between the Greater Khingan and the Lesser Khingan mountain ranges in the west and east, respectively, and meets the Second Songhua River near Da'an to form the Songhua River. The river is prone to flooding, as occurred most recently in 1998 and 2005.
