Archaeological discoveries at the Sanxingdui and Jinsha Site have established that the area surrounding Chengdu was inhabited over four thousand years ago, in 18–10th centuryBC. At the time of China's Xia, Shang, and Zhou dynasties, it represented a separate ancient bronze-wielding culture which—following its partial sinification—became known to the Chinese as Shu. Shu was conquered by Qin in 316BC and the settlement re-founded by the Qin general Zhang Yi. (A Chinese legend explains the town's nickname "Turtle City" by claiming Zhang planned the course of his city walls by following a turtle's tracks.) Although he had argued against the invasion, the settlement thrived and the additional resources from Sichuan helped enable the First Emperor of Qin to unify the Warring States which had succeeded the Zhou.