dynasty in which China was unified under the first emperor, Qin Shi Huang Di. He established central rule and standardized weights, measures, coins, and the writing system. Some claim that it was his idea to create the Great Wall in 214 B.C. to protect China from invasion. He was a particular believer in the notion of immortality and is famous for his terracotta army of over 7,000 life-size pottery soldiers, found buried near his tomb in the early 1970s.