[3] The river's source is the western slopes of the Greater Khingan mountains of Inner Mongolia.

In its lower course, it forms the boundary between China's Inner Mongolia, and the Mongolian Republic[2] until around 48°01′59″N 118°08′03″E / 48.033179°N 118.134290°E / 48.033179; 118.134290, the river splits into two distributaries.

The left branch (the Halh River proper) flows into the Buir Lake at 47°53′44″N 117°50′08″E / 47.895556°N 117.835556°E / 47.895556; 117.835556; discharge from that lake at 47°57′00″N 117°48′51″E / 47.950011°N 117.814270°E / 47.950011; 117.814270) is known as the Orshuun Gol [fr] (Mongolian: Оршуун гол, Chinese: 乌尔逊河; pinyin: Wūěrxùn Hé).

From May to September 1939, the river was the site of the Battles of Khalkhin Gol, the decisive engagement of the Soviet-Japanese border conflicts.

Soviet and Mongolian forces defeated the Japanese Kwantung Army.