Manchuria, historic region of northeastern China, now known in China as the Dongbei Pingyuan (Northeast China Plain). The region comprises the provinces of Heilongjiang, Jilin, and Liaoning; and the eastern part of Inner Mongolian Autonomous Region. Historically the region included a much larger area extending west to what is now Mongolia.

The name of the region is derived from that of the Manchus, a Mongol people similar, ethnologically, to the Tungus. The warlike, nomadic Qing (Manchu) tribes roamed the Manchurian plain until 1644, when they invaded China and established the Qing, or Manchu, dynasty, which ruled China until 1911. The Manchu rulers refused to permit development of Manchuria and even forbade Chinese immigration into the region until the late 18th century. Continual Russian encroachments on the northern frontier resulted in agreements between China and Russia in 1689, 1858, and 1860, fixing the Sino-Russian frontier along the Amur River to the Ussuri River.

By the end of the 19th century the Chinese composed approximately 80 percent of the Manchurian population. The vast potential of Manchurian resources became the object of a struggle between China, Russia, and Japan for control of the region. After the Chinese defeat in the First Sino-Japanese War (1894-1895), Japan briefly gained control of the Liaodong Peninsula (see Sino-Japanese Wars). In 1898 Russia obtained a 25-year lease of the southern peninsula, including Dalian and Port Arthur (now part of the municipality of Dalian). Russia occupied Manchuria from 1900 until its defeat in the Russo-Japanese War in 1905.

In 1931, from their stronghold on the Liaodong Peninsula, the Japanese invaded Chinese-held territory in retaliation for an incident of alleged sabotage (Second Sino-Japanese War). Ignoring orders from the government in Tokyo, the army drove Chinese troops from Manchuria, then annexed Jehol, a Chinese province, to the three provinces of Manchuria. The Japanese established a puppet state, called Manchukuo, with Henry Pu Yi as emperor.

After Japan's defeat in World War II (1939-1945), Manchuria was briefly occupied by the Soviet army (1945-1946). Then Chinese troops returned, and in 1949 Communist rebels took control.

In 1949 part of Manchuria was added to the newly created Inner Mongolian Autonomous Region; the remainder was divided into six provinces making up the North-Eastern Region, one of six large administrative units of China. The number of Chinese provinces was reduced to four in 1954, and to three (Heilongjiang, Jilin, and Liaoning) in 1956.