According to the "history of the Tang Dynasty" records, the Empress of Tang Gao Zong, Li Zhi and concubine Wu Zetian gave birth to a son, named Prince Zhang Huai, he is Li Xian. Although Tang Taizong Li Shimin sealed Li Zhi as a prince, he was sickly, weak and temperament. After Li Zhi succeeded, he often couldn't work because of the sick, so Wu Zetian began to work instead of him. In 659, the Empress of Gao Zong appointed Li Hong as the crown prince, Li Hong was honest, but he was soon poisoned by Wu Zetian. In 673 years, Gao Zong appointed Li Xian who was 22 years old as the crown prince, and arranged him to deal with the things of state. Li Xian was good at learning, and he had the talent on the things of government. But Wu Zetian was trying to succeed in throne, so she was harsh to Li Xian very much, Li Xian was demoted into Tianping mountain the area of Bazhou as civilian. According to historical records, in the year 678, Wu Zetian ascended the throne for 23 years, the country was renamed Zhou