History
The question of exactly where the people of Japan originated is still under debate. Physically, they are related to people in other Asian countries. For example, most Japanese babies are born with a bluish mark at the base of the spine, a trait common to Asians. (Pediatricians in the West, who are unfamiliar with this birthmark, sometimes wrongly suspect that something is amiss.) Historically, the truth is that large numbers of Chinese, Koreans, and Southeast Asians--including the Ainu, an indigenous people who came to the islands earlier--migrated to Japan, resulting in a blend of facial and physical features in the country's present-day people.
(excerpt from p.17)