Wikipedia says they are known as "first peoples":
https://en.wikipedia.org/wiki/Indigenous_peoples
For the most part, that is literally true -- they were the first group of humans on that land, humans having originated in Africa.
These books make the point that agriculture is the essential difference between indigenous and non-indigenous peoples. Agricultural technology enables people to get on boats and take the land of non-agricultural societies. It enables greater popular density and wealth.
This happened all over the world in the same progression, at roughly the same times.
In America, the indigenous peoples came from Asia by way Alaska more than 10,000 years ago. Then Europeans came by boat ~500 years ago.
I don't know much about the history of Japan, but it seems to have been inhabited by non-Japanese/Chinese and then the Chinese ancestors of Japanese conquered the land. If anyone knows details I'm interested.
https://en.wikipedia.org/wiki/J%C5%8Dmon_period
https://en.wikipedia.org/wiki/Ainu_people
China was of course one of the first agricultural societies, and this enabled them to expand their territory rapidly, on the Asian continent and beyond. There were indigenous peoples living all over the Phillipines, Polynesia, Hawaii, etc. but they look "Asian" now because of the Chinese expansion. There were two different groups of people that collided.