Why do you say that the securities established by a few nobles

The larger ones are Northern Wei (Tuoba, Xiongnu), Northern Qi (Yuwen, Xiongnu), Liao (Yelushi, Qidan), Jin (Wan Yan, Nuzhen), Xixia (Li, Qiang), Yuan (Borges, Mongolia) and Qing (Aisingiorro, Manchu). Strictly speaking, the Sui and Tang Dynasties of the Five Dynasties were also founded by foreigners. If we look at the history carefully, the ancestors of Emperor Wendi of Sui Dynasty and Li Yuan were aristocrats of northern minorities, because in the Tang Dynasty, there was a social reality that the emperor's daughter was also worried about marriage, because at that time, famous families paid attention to marriage, and only Li, Zheng, Cui, Liu and other big names were famous, and these big names were divided into many tribes, such as Li's surname, but not all of them. Only Li surname is a nobleman in Longxi. At that time, it was difficult for other surnames to marry these noble surnames. Although the emperor of the Tang Dynasty was also surnamed Li, he did not belong to Li in Longxi, but was a descendant of the northern nomadic people, so some big families were still reluctant to marry them.