China’s first imperial dynasty. It was founded by Prince Zheng, ruler of the Zhou vassal state of Qin. Unlike rival Chinese states, Qin used cavalry not chariots in battle and early adopted iron weaponry. It ensured a regular food supply by developing a system for land irrigation. Based in Shaanxi, it began to expand its territories c.350 bc. Under Zheng, it overthrew the Eastern Zhou and conquered (256–221 bc) all Zhou’s former vassal states. Zheng then took the title Huangdi and is best known as Shi Huangdi (First Emperor). He died in 210 bc and his dynasty was overthrown four years later. From that time, though China was sometimes fragmented, the concept of a united empire prevailed. From Qin is derived the name China.