The Spring and Autumn Period continued for about 300 years. By the 5th century BC, there were only seven main Chinese states left. They had taken over all the smaller areas. These states continued to fight each other. Historians call this period the Warring States Period due to wars and fights among these states. In 221BC, Ying Zheng, king of the State of Qin, united all the seven states. He made himself the Emperor of China and founded the Qin Dynasty.