On boats.

From australia and polynesia.

They were black and did not have east asian features like todays native Americans, who arrived over the land bridge which connected Asia with what is now Alaska.

The point is GFS, that before we go calling todays Native Americans "Aboriginal", we should be sure that they were the original inhabitants - it is a conveniently enjoyable irony that the race of people whose history places doubt on that claim were in fact Australian Aboriginals.