The cause of the Anshi Rebellion was that Emperor Xuanzong trusted An Lushan too much, and some people said that An Lushan was going to rebel. He didn't believe it at all, only the Anshi rebellion. So An Lushan successfully rebelled on this basis, and then pushed the Tang Dynasty court originally in the north to the south.

At that time, because the main fluctuation range of Anshi Rebellion was in Hebei, it basically had no influence on the south, so that after the Tang Dynasty moved directly to the south, it still had enough financial resources to maintain the operation of a country. Do you know that?/You know what? It is how rich Jiangnan is. After the Tang Dynasty had money, it began to recruit soldiers, so with soldiers, he could successfully resist the invasion of foreign enemies.

Moreover, in 150 years after the southern expedition of the Tang Dynasty, many outstanding generals appeared in the Tang Dynasty. They can not only resist foreign enemies, but also take the initiative to fight against those princes under the condition of stabilizing the sustainable development of the country. However, the farther back, the worse the emperor penguins get. It's probably an old saying, the national luck is exhausted. Not only will they not employ people, but they will also make their already strong army weaker and weaker because of mistakes in employing people.

Besides, they don't have their own abilities. If you say that he can't choose people, forget it. He doesn't have a way of governing the country, which directly affects their own national economy. The last emperor was poisoned by Zhu Wen, and the prosperous period of the Tang Dynasty ended.