From which dynasty did the Japanese go to Japan? What is the reason?

The earliest civilization in Japan can be traced back to the Paleolithic civilization 10,000 years ago, the so-called rope age, which means that the island of Japan was already inhabited at that time. Later, in the Qin Dynasty, Xu Fu's fleet arrived in Japan (both China and Japan have a lot of legends, but there is no tangible archaeological evidence), which opened the exchange between Japan Island and Chinese mainland. Later, with the advanced agricultural (rice planting) and industrial (metal smelting) technology brought by mainland immigrants, Japanese civilization began to accelerate, and it is impossible to verify how many mainland immigrants Japan absorbed during this period.