During the Kaiyuan period of Emperor Xuanzong of the Tang Dynasty, although the social economy reached unprecedented prosperity and a prosperous situation appeared, at the same time, due to the development of feudal economy, land annexation was accelerated. "The houses of princes and rich men are better than fields, and they are not afraid of the articles of association." As a result, "Li Tuo lost his job, his registered permanent residence was engraved, and he abandoned elm and moved away." The land equalization system was destroyed, and the farmers lost their land and became refugees. In addition, the highest ruling clique in the Tang Dynasty became increasingly corrupt. From the end of Kaiyuan, Emperor Xuanzong of the Tang Dynasty lived a dissolute life all day. Yang Guifei's family is all over the world and profligate at will. There are 700 palace craftsmen who embroider brocade for imperial academy, and Yang Guifei's sisters spend millions every year. Yang's five brothers and sisters, one of whom is a big man, usurped official positions. Horses and chariots serve the royal family, shine on Beijing, and pay tribute. Every building costs tens of millions. "The decay of the ruling class increased the burden on the people and made them in dire straits.