Let's look at the Jomon/Ainu thing. It's pretty obvious to any researcher that there's little difference between the two "categories" of people. In fact, both belong to a branch off the main East Asian type.
On the other hand, there are substantial cultural and historical differences between them. The Jomon may also be identified as the Emeshi people who lived in Northern main islands and along the East Coast.
These are the people whose culture is on display in those Japanese children's cartoons featuring ghosts, magic badgers and regular looking pottery (distinct from the modern era).
During the development of the Empire, roughly 600 AD to 1300 AD, the Royal family battled with the technologicaly equal Emeshi and finally reduced them to a subordinate class we know as the Samurai. At the end of the period the Emeshi/Samurai were relocated to Western Japan ~ roughly to Fukuoka ~ for the purpose of providing Imperial punch throughout this most developed and wealthiest part of the near-Empire.
With the coming of Tokugawa, the Samurai were demilitarized but were then appointed to replace any pre-existing lower nobility throughout the country.
There was a price for relocating the Emeshi. For one there was the question about who would guard the Northern approaches to the Main Islands. Apparantly NOBODY got that job so the mainland dwellers we now know as the Ainu moved in!
They had not been as technologically advanced as the Jomon/Emeshi, but they were sufficiently powerful they could develop a widespread seaborne trading empire of their own. When you see bears involved in those cartoons about medieval Japan, that's the Ainu.
Japan also had a population drawn from Mainland Asia that can be called the Yayoi ~ there's some concern that older views of the Yayoi are wrong ~ that is, that the idea that the Imperial family, the Daimyo and the lower nobles were just a Yayoi upperclass was not all consistent with the ancient tombs and archaeological findings.
Recently it was finally established that the Emeshi people had developed agriculture and hadn't been just a bunch of wandering fishermen with large razorblades!
At the same time ideas about the Yayoi have begun to change. The old view was that the Impeial families and the Daimyo rose up from the broad masses of the Yayoi.
The reality seems to be that whatever was going on with the Yayoi, they had simply faced the same fate as the Emishi in the Middle Ages at the hands of an invading Royal family albeit a couple of centuries earlier due to their proximity to Korea.
More recently a major discovery was made regarding the identity of the Royal family (or the invaders most represented by the Royal family). That is that they were NOT KOREAN although they came from Korea. In fact, they conquered Korea during the early period of the Dark Ages (535 AD or thereabouts), and went on to conquer the wealthier Southern parts of Japan shortly thereafter.
The question now is where do these guys come from ~ and it's a humdinger.
Remembering that we somehow have to get otherwise illiterate Buddhists into Korea to then cross over to conquer Japan on horseback, we have to find some illiterate Buddhists!
Ain't no easy task ~ Buddhism and literacy go hand in hand in East Asia. Most Buddhists have vast quantities of scriptures and it requires literate people to copy them over and keep them in shape so the religion, culture and philosophies can be spread to others.
The biggest bunch of illiterate Buddhists turn out to be the Yakut or Sakha people in the region of Siberia and Manchuria. They also were very warlike, herded all sorts of animals, and were quite aggressive.
Today there are about 25 million Yakut ~ after 200 years of fairly close contact with European Russians they constitute quite a racial mixture so if you look up their pictures you're going to see some "white folk" ~ and RED HAIR. Some of the "red hair" is also of ancient origin in India.
Way back in Buddha's day, the Sakha or Saka, lived in Nepal and those parts of the North Indian plain near the Nepalese foothills.
They'd come into that region from Manchuria (their original home) sometime in the distant past. During the period of their ascendancy, a Sakha Prince we call Buddha, achieved satori in real time (enlightenment) and set about reforming Hinduism.
Although he had some success, the Sakha began to lose power as yet other invaders came into India (which has been going on since time began), and some time about 200 AD the Sakha were driven from North India and Nepal by the resurgent Hindu Revival. The Sakha fled North and East across China and right back into Manchuria and Siberia.
For a variety of reasons they lost all their masters at writing, but they did keep some of their records.
Archaeologists and historians are working this stuff over, plus all the DNA tests these guys will let them take, and their "history" since their flight from Nepal has been blocked out a little better.
Note, this group took with it plenty of large bosomed Indo-European and Dravidian type women, and today those same large bosoms (let's call them "bazoombas") show up occasionally throughout the Japanese population but most specifically among the families of the former nobility, the Samurai and, lo and behold, the Royal families!!! (Ta-Da)
Otherwise Japanese women are known for their very flat curvature.
In the end, although the "hips don't lie", the teeth tell a tale. Roughly 60% of today's Japanese have teeth typical of the Chinese. Roughly 40% have teeth typical of those found among the Jomon, Ainu, Emeshi and some other groups here and there in hidden valleys and high mountains in the Himalayas.
There are also some Japanese who have teeth just like the white folks in the Punjab. The population is mixed enough after centuries of human slavery, feudalism, warfare and class consciousness that you can find all the major toothtypes in the islands in individual families.
The Yayoi turn out to have been a mixed population of people from all over East Asia. They came with rice culture. They are also the source of basic Japanese language grammar and vocabulary. During the late Middle Ages the Japanese really did bring in literate Buddhist monks and artisans to beef up their technology and culture. Those monks came mostly from Korea and they added a major portion of Japanese language vocabulary and even influenced the grammar.
The Emeshi language became lost to history as it was swamped in a vast tide of Yayoi and Korean words.
The conclusion is that the Ainu have little to do with the modern Japanese population whereas their cousins, the Emeshi, are still a powerful presence (genetically speaking). The illiterate Buddhists from Nepal who ran the country up until recent modern times found their history, religion and language supplanted by Korean "servants" shipped in to improve the economy.
Good report, thanks.