Chang 'an and Xi 'an are two different concepts. Chang 'an is a historical place name and Xi 'an is a modern place name. The differences between them are as follows: different historical status. Chang 'an is the historical name of Xi 'an, which originated in the Han Dynasty. At that time, Emperor Gaozu Liu Bang chose to establish a new capital in Chang 'an Township (now northwest Xi 'an), and promoted Chang 'an Township to the county level, named Chang 'an County. Subsequently, Chang 'an became the capital of several dynasties and gradually developed into an important political, economic and cultural center. Xi 'an is the result of the historical evolution of Chang 'an. In the Ming Dynasty, Chang 'an changed its name to Xi 'an in order to stabilize the northwest, which means "Xiping". Modern geography is different. In modern administrative divisions, Xi 'an is a city, but Chang 'an County no longer exists, and the county territory of Chang 'an County has become a part of Xi 'an.