I also read that the Ainu shared a common origin with the american indians. I forget the source...thinking...thinking...crap. You can yahoo it or google it and find the story.
I think your judgment here is pretty much on target, SG. What evidence was cited for the link? Given that there is no good evidence that `[A]merican [ I]ndians'
themselves share a common origin, it would be kind of difficult to make the still more outré case that the Ainu are related to all of 'em, eh? (We can leave Greenberg's supposed `Proto-Amerind' supposed grouping out of this; reputable historical linguists who actually
do linguistic reconstruction showed long ago that his `method of mass comparison' would identify virtually
any two lanuages chosen at random as genetically related). Ainu has suffered the same fate as Basque in Europe and other language isolates: there seems to be a compulsion to find other linguistic families to group them with, even if the evidence doesn't even support the ghost of a connection. Let's just say that any linkage of the Ainu to any other identified human population faces a burden of proof which no one has even
begun to meet.
My professor also told us that the yayoi actually originated from a proto-korean stock in Pusan, and that the yamato uji was a korean clan that settled in ainu japan due to overpopulation. The big red dot in the japanese flag was a symbol depicting lord ameterasu, who is really the korean sun goddess of some sort. He would jokingly say that japanese are just koreans with a little bit of ainu in them. I don't know, I am not an expert on it. Just sharing what my Prof taught me in uni. History is quite interesting, indeed.
The picture you've painted here is a speculative fantasy unsupported by any kind of evidence, linguistic or physical. Japanese and Korean have yet to be shown to be genetically related by the acid test of historical linguistics: systematic reconstruction of proto-vocabulary using the standard comparative method, with detailed working-out of the sound changes that link descendent subgroupings to their common ancestors. The vast difference between their respective vocabularies, showing not a trace of lexical resemblance beyond the same kind of random resemblances one finds between English and Mandarin or Dutch and Swahili, decisively undercuts any hoped-for use of linguistic evidence to link the Korean and Japanese populations; and we are still very far from being able to identify genetic tags that would permit
any statements, one way or the other, about genetic relations amongst the Korean, Japanese and Ainu.
It's true that history is
extremely interesting. But speculation purporting to be history is actually rather tedious; it almost invariable winds up supporting someone or other's contemporary self-serving agenda, typically at someone else's expense. Folk beliefs and `oral history' so frequently turn out to be, in effect, charters for claim to (or denials of) some group/faction/sect's legitimacy that all they do, in the end, is provide grist for cynical reflections about how little people really care about the truth when their own advantage is involved. And we already
know that, right?
What I find somewhat odd is the idea that a single genetic group in feudal and post-feudal Japan would be linked to a single occupational specialization along the lines you're asking about. That sort of things seems to've happened in India, where ethnicity and profession are tightly linked in the caste system; but mediæval Japanese was organized on rather different lines, as I understand it. It's true that certain families, and clan groupings of families, had different specializations in some cases, but my impression is that the lines separating samurai and non-samurai families was somewhat fluid early on. Many of the proto-samurai seem to have been displaced peasants who were skilled with a variety of weapons and worked as mercenaries, guards and `enforcers' for wealthy merchant clans. It's hard for me to see how this formation process could have wound up being as ethnically exclusive as the question—did
the samurai belong to
the Ainu population—seems to entail.