Manchu (măn´chōō), people who lived in Manchuria for many centuries and who ruled China from 1644 until 1912. These people, related to the Tungus, were descended from the Jurchen, a tribe known in Asia since the 7th cent. They were first called Manchu in the early 17th cent. Originally pastoral nomads in Manchuria, the Manchu (or Jurchen) swept into N China in the early 12th cent. but were forced by the Mongols to withdraw in the mid-13th cent. The Manchu settled in the Songhua River valley and developed an agrarian civilization. Under the emperor Nurhaci (1559–1626) they secured the allegiance of many tribes and increased their territory. The Manchu claim of relation to the Ch'in dynasty of China was the justification for conquering China in the 17th cent. and establishing the Ch'ing dynasty. The Manchu tried to keep themselves from being absorbed by the Chinese, but when the dynasty was overthrown in the 20th cent. these efforts failed; gradually, they have become part of the general Chinese population.