Who were the Emishi?

I am pondering "Japan": not as an archipelago of land, but as zones of sea.

The southern Japanese islands, and the south half of Honshu, is Yayoi/Jomon. This is where Nipponese was ancestrally spoken; "Yamato" is a term sometimes used. Also wider Japonic south to Okinawa...

...and part of Korea. When Japonic was purged off of Korea remains a question, I believe. Clearly Korea was the Yayoi homeland, even Kofun. Once "Cipan-guo" was its own empire, its interests in the peninsula conflicted with the Tang interests; which the Tang won. What I don't know is if those Japanese interests were a colony, or local holdouts who naturally kept ties over the strait. I expect, the latter (I have my eye on Gaya). So there's one zone: the Korea-Honshu sea zone.

Ainu when first noted (by Russians!) was spoken along north Hokkaido, Sakhalin, and the Kurils. That's another sea zone.

Last March, I was considering the Matsumae holding in south Hokkaido. Now: the Matsumae considered themselves full Japanese. They spoke that language, were the Yayoi/Jomon mix, bowed to the Emperor, all-o'-that. By then they knew of Ainu north of them and that they were different. So even in the nineteenth century (as we term it), when all Japanese claimed the same culture, those up in that north island weren't integrated into the tax system. This Matsumae autonomy could be possible only by geography, and the technology at the time. I think we have here an intervening sea zone: between southern Hokkaido, and northern Honshu. If the shogun had trouble controlling this far with eighteenth-century tech; how well could the emperor control it with eighth-century tech?

In the Middle Ages, before the Matsumae, south Hokkaido and north Honshu were controlled by "Emishi". The old (south) Japanese - the Yamato - considered them like the Chinese or the Russians considered tatars. Like barbarians.

I don't think the Emishi were Ainu. I think the Yamato-Japanese at the time had boats and could meet some Ainu, up north; so saw, likewise, that the Emishi didn't behave like the Ainu, anymore than either of them behaved like Koreans or Chinese. You would think, otherwise, that the Japanese should have lumped the Emishi with the Ainu together - at that time, not now.

So what language did the Emishi speak? What was their culture other than "fighting the Yamato"? Maybe the Emishi were the indigenes of Honshu, before the Kofun came. Maybe what we call "Japanese" is the old Gaya language. In this case the Emishi were simply crushed between the new Japanese empire, and the Ainu of north Hokkaido.