If they are unlike modern Native Americans, what group/who are they like? Surely not caucasians. =:P
The original Japanese, the Ainu people.
Not those Korean invaders we know as modern Japanese. There are still groups of them living on the Northern Islands. Ian Fleming noted their "more Caucasian" appearance and so hid Bond amongst them in "". The movie version, as usual, screwed it up and had the babe he was living with be a modern Japanese.
The kelp beds run all the way from Japan to South America. The Ainu people (think Kennewick Man) come from Japan.