After Liu Bei captured Chengdu, he called himself "King of Hanzhong". Why is there no Zhao Yun among the four generals?

Zhao Yun's background is not good. In that cremation era, a good background was very important. It is not unreasonable for Liu Bei to call himself a descendant of great men. Moreover, in most battles, Zhao Yun is mainly the captain of the guard who guards Liu Bei's family and Liu Bei's family. It can be seen that Liu Bei absolutely trusts Zhao Yun. In fact, Liu Bei is very kind to Zhao Yun. Although he gave a small official less honor, after all, Zhao Yun didn't have much positive exploits, so Liu Bei gave him an imperial envoy. This position is very small. As a famous loyal general, Zhao Yun has no cronies, money and power. The imperial leader suddenly gave Zhao Yun a bunch of thugs, and Liu Bei himself breathed a sigh of relief. This was a win-win situation. In fact, if Liu Bei didn't like Zhao Yun, Zhao Yun would have been finished long ago, because he provoked many officials. Liu Bei is actually Zhao Yun's biggest umbrella and Zhao Yun's most reliable and solid political backing.