The State of Wei, was a Zhou Dynasty vassal state during the Warring States period (475-221 BC) of Chinese history. Its territory lay between the states of Qin and Qi and included parts of modern day Henan, Hebei, Shanxi and Shandong. After its capital was moved from Anyi to Daliang (today Kaifeng) during the reign of King Hui of Wei, Wei was also called the state of Liang.

The origins of the Wei ruling house can be traced back to the Zhou royalty; Bigong Gao, a son of King Wen of Zhou, was enfeoffed in the land of Bi, from which his descendants took their surname. After the destruction of the State of Bi by the Xi Rong people, Bi Wan, a scion of the ruling house, escaped to the State of Jin, where he became a courtier of Duke Xian of Jin, accompanying his personal carriage. After military successes in an expedition, Bi Wan was then enfeoffed in the land of Wei, from which his own descendants founded the house of Wei.

The military prowess of Qin broke the coalition forces of the States of Wei and Han at the Battle of Yique in 293 BC. Wei surrendered to Qin in 225 BC, after the Qin general Wang Fen flooded Daliang with water from the Yellow River.