The Liao River is the principal river in southern Northeast China, and one of the seven main river systems in China. Its name derived from the Liao region, a historical name for southern Manchuria, from which the Liaoning province, Liaodong Peninsula and Liao dynasty also all have derived their names. The river is also popularly known as the "mother river" in Northeast China. Coursing 1,345 kilometres (836 mi) long, the Liao River system drains a catchment basin of over 232,000 square kilometres (90,000 sq mi), but its mean discharge is quite small at only about 500 cubic metres per second (18,000 cu ft/s), about one-twentieth that of the Pearl River. The Liao River has an exceedingly high sediment load because many parts of it flow through powdery loess.

Manchuria is a term that refers to a region in Northeast Asia encompassing the entirety of present-day Northeast China, and historically parts of the modern-day Russian Far East, often referred to as Outer Manchuria. Its definition may refer to varying geographical extents as follows: the Chinese provinces of Heilongjiang, Jilin, and Liaoning but broadly also including the eastern Inner Mongolian prefectures of Hulunbuir, Hinggan, Tongliao, and Chifeng, collectively known as Northeast China; the aforementioned regions plus the homelands of ancient Jurchen and their descendant Manchus, parts of these region were ceded to the Russian Empire by the Manchu-led Qing dynasty during the Amur Annexation of 1858–1860, which include present-day Amur Oblast, Primorsky Krai, the Jewish Autonomous Oblast, the southern part of Khabarovsk Krai, and the eastern edge of Zabaykalsky Krai, collectively known as the Outer Manchuria or Russian Manchuria.