China is one of the world's oldest continuous (still alive) civilizations. Turtle shells with writing like ancient Chinese writing from the Shang Dynasty () have been carbon dated to about 1500 BC. They say that China began as city-states in the Yellow River valley. Many people say that China became a big Kingdom or Empire in 221 BC. The Qin () emperor Qin Shi Huang made everyone write the same way. He also had ideas about the state which he based on legalism and fought Confucianism. This began what we call the Chinese civilization. Ancient China fought wars and Civil wars and was also sometimes conquered by other people.