Why is the history of Xia and Shang Dynasties not recorded? But do the descendants of Dayu know?

In my opinion, the main reason is that when the measurement was unified, Qin Shihuang wrote words and so on, and people could not interpret ancient books. Coupled with the cultural preservation technology at that time, there were few materials that could be handed down, and the incident of burning books and burying Confucianism. Let those bachelor of arts cut off the inheritance. As for Dayu's flood control, his incident had a great influence on the people. When a message flows at the grassroots level, there is almost no way to stop it.