The Qin Dynasty (Chinese: 秦朝; pinyin: Qín Cháo; Wade–Giles: Ch'in Ch'ao; IPA: [tɕʰǐn tʂʰɑ̌ʊ̯]) was the first imperial dynasty of China, lasting from 221 to 207 BC. The Qin state derived its name from its heartland of Qin, in modern-day Shaanxi. The strength of the Qin state was greatly increased by the legalist reforms of Shang Yang in the 4th century BC, during the Warring States Period. In the mid and late third century BC, the Qin accomplished a series of swift conquests, first ending the powerless Zhou Dynasty, and eventually destroying the remaining six states of the major states to gain control over the whole of China, resulting in an unified China.