Let's talk about it from three aspects.
Geographical location that can't be ignored. If there is a war, Chang 'an's position is really unique, and the country is easy to defend but difficult to attack. This place lives in Guanzhong, with Douxin in the east, Wuguan in the south, Sanguan in the west and Xiaoguan in the north. It can be said that there are protective barriers on all sides. Don't worry too much during the war. Think about the picture, let you play everywhere, I'll just sit still in Chang' an, what a vivid boss!
2. Material basis. If the geographical location is superior, everything will be easy. War is not a problem. People live and work in peace and contentment, and agriculture is also quite developed. Historically, Chang 'an is located in Guanzhong Plain, with superior climate, fertile land and rich products, which provided the most basic guarantee for people's lives.
Which king doesn't love such a place, how can the country not prosper?
3. Foreign exchange. Today's Chang 'an is called Xi 'an because it is closer to the western frontier. This is also an advantage that has to be said, because it is close to ethnic minorities. On the one hand, some tyrannical kings can attack them and get more materials to enrich their country. On the one hand, they can promote the change of production mode and promote cultural diversity and prosperity through exchanges with other ethnic groups. It is said that Chang 'an is also the starting point of the Silk Road. Isn't this another traffic advantage? This has further promoted the development of the country and foreign countries, which is the same as the introduction of grapes, corn and other crops into China. Only by strengthening exchanges with the outside world will the country have more possibilities for prosperity and development.