The reason why rulers of past dynasties took a fancy to Xi 'an was related to the geographical location of Xi 'an. Xi 'an is located in Guanzhong Plain, bordering Qinling Mountains in the south and Weihe River in the north, with mild climate and fertile land. Historical records? "Stay in Houjia" records the praise of the Han Dynasty to An: "Fu Guanzhong left to believe, right to Longshu, fertile land thousands of miles. The south has the grace of Bashu, and the north has the benefit of being in a tiger's position. It is banned on three sides and controlled by princes on one side. The princes are stable, the rivers and rivers embrace the world, and the west gives the capital; The vassal has changed, and going down the river is enough to defeat. This so-called Jincheng is a thousand miles away, and the country of abundance is also. "