All people surnamed Liu are descendants of Liu Bei. If they are not descendants, they are related by blood.

No, Liu Bei is not the first surnamed Liu, so it can't be all his descendants.

1 The Jing nationality was originally called Yue nationality, with a population of nearly 20,000 and a surname of 3 1. It lives in the southern Xinjiang islands of Guangxi, and Liu's population accounts for 20% of the Jing nationality, which is the first surname of this minority. There are three surnames of Jing people in Vietnam, one is Liu who is completely integrated into the Vietnamese nation, the other is Liu who is formed by Vietnamese using Chinese characters, and the other is overseas Chinese who immigrated to Vietnam after modern times. However, it is difficult to distinguish these different surnames Liu today.

After the Qi surname Tao Tangshi and Emperor Yao (Xun), it was sealed in Liu (now Tangxian County, Hebei Province) and the Qi surname Liu was established.

"Tongzhi" Volume 26 "Family II" said: "Yao is divided into six, and Tang, Du, Fan, Liu, Wei and Qi are all surnames, and Yao never died!

Originated from the surname of Ji, it originated from the fief given by King Ding of Zhou to his younger brother Ji, which belongs to the name of fief.

Source 5: Give or change the surname.

China is a multi-ethnic country, and the long-term ethnic integration is also reflected in the evolution of surnames. Liu is a typical example.