Why was Xi 'an in Tang Dynasty called Chang 'an? And why did you become the capital at that time?

Chang 'an is the ancient name of Xi 'an, the first capital called "Jing" in history, and the first real city in history.

At this time, the capital of Zhou Wenwang was established, and Fengjing was built. When King Wu ascended the throne, Haojing was built, which was collectively called Fengjing, hence the name "Hao". In the fifth year (the first 202 years), Emperor Gaozu established Chang 'an County, and built Changle Palace on the basis of the south bank of Weihe River, the north side of Epang Palace and Qinxingle Palace. In the seventh year (the first 200 years), Emperor Gaozu built Weiyang Palace, and the capital moved here from Liyang in the same year. Because it is located in Chang 'an Township, it is named Chang 'an City, which means "long-term stability".