The Ulan Moron (Mongolian: ᠤᠯᠠᠭᠠᠨᠮᠥᠷᠡᠨ, Ulaan Mörön, lit.

"Red River"; Chinese: 乌兰木伦, p Wūlánmùlún), Mar Qu (Tibetan), or Tuotuo River (沱沱河,[a] p Tuótuó Hé, lit.

"Tearful River";[1][b] Tibetan: ཐོག་ཐོག་ཆུ་, ZYPY: Togtog Qu) is a 336 km (209 mi) long river, located in Qinghai province in the People's Republic of China.

Although the Dangqu has been found to be the source of the Yangtze under the usual modern criteria, the Ulan Moron has been traditionally regarded as the main river and source.

It belongs to the East China Sea watershed basin.