Are all the people surnamed Yu Hui?

no.

For Hui people, the general surname of Hui people is no less than: Na, Ma, Niu, Sa, Ha, Sha, Sai, Su, Hu, Shan, Bao, Mu, Su, Hao, Sa and Ma. Ma, Niu, Yang, Tie, Hai, Sha and Su are all the most popular names of Hui people.

As for this surname, it is obvious that it is a small surname among Hui people. Generally speaking, the surname of Hui people is rarely mentioned. In contemporary China, the population of Yu surname has reached 6.42 million, which is the 39th surname in China, among which Han nationality is still dominant, so the surname Yu is mostly Han nationality.