He became ruler of the state of Qin in 246 bc and declared himself emperor in 221 bc after overthrowing the Zhou and their vassal states. He ordered that the frontier walls in northern China should be joined together and extended to make the Great Wall of China and enlarged his empire into southern China. He could not accept the Confucian belief that an emperor should follow traditional rites, and so ordered the burning of all Confucian books, the banning of Confucian teaching, and the killing of scholars. In death as in life he was heavily guarded: close to his burial mound outside Xi’an stood an army of life-size pottery warriors and horses. The dynasty outlasted him by only three years, but he had imposed lasting unity on China by standardizing scripts, weights, and measures.