Well, the whole thing just seems impossible to sort out. What we have is evidence (considering the Ainu and the mummies of Urumchi) that the some ancient inhabitants of Japan and much of Asia were caucasian types. It seems to me that the oriental type may have come from South American after the cataclysm 12500 years ago and spread and intermingled a bit with the Ainu, but that most of that "type" were driven West, toward Europe. Of course, they may have originally been driven East FROM Europe at another time since we have the evidence of Cro-Magnon man in Europe VERY early (cave paintings, etc). That people move back and forth and mix around is certainly true, and that sure makes things difficult, but I also think that there is some evidence that type is attracted to type MUCH of the time.
Then we have the language problem. For example, Spanish and/or Portuguese is the main language of most of Central and South America, but it was imposed and imported. Same with English in North America and Australia. In fact, English is the modern day "lingua Franca and nearly all science is done in English. If you don't publish in English, nobody knows who you are.
So, can we really rely on language to know who is who and where they came from? Or is language more an indicator of what kind of culture is dominant at any given time?
Consider the Akkadian language rendered in Sumerian cuneiform...
Just so many questions... and I suspect that if we work on other things, like cleaning our "vessel", we might find the answers a lot sooner and easier than if we keep knocking our heads against brick walls.