The 38 Years' War was, from what I understand, the final major conflict between the Emishi and Yamato people. It began with a strong showing by the Emishi, who struck numerous blows against the Yamato kingdom, and it seems as though it was only the betrayal of the Shiwa tribe that did in the Emishi. So, what if the war had gone the other way? What if the Shiwa had not changed sides? Could such a victory result in the Emishi tribes banding together into a more permanent kingdom and survive? How would the history of Asia change if Japan was only half the archipelago?
 
Well on base to the wiki information then I would say that the Yamato situation was very dangerous and in the verge of to be defeated if not had been for the Yamato's cooptation of these clans' leaders that seems them were key in reverse the course of the war.
Also was only after this victorious war that Yamato's expansion to become in unstoppable and irreversible their consequences, but as well (according the Wiki info.) in those times the Emjis seemed that were more than able to not only defeating but stopping the Yamato expansion.

Perhaps an Emishi victory would be having success in consolidating the borders between both groups.
Also would begin to reverse the Historical development and a side of the mentioned hypothetical naval expansion of Yamato, at all;... at least in my opinion seemed probable that if not succeed the opposite, at least the Emishi would be able to survive and keep their culture and probably to expand and/or consolidate their ruling, at least in their own lands.
 
Perhaps an Emishi victory would be having success in consolidating the borders between both groups.
Also would begin to reverse the Historical development and a side of the mentioned hypothetical naval expansion of Yamato, at all;... at least in my opinion seemed probable that if not succeed the opposite, at least the Emishi would be able to survive and keep their culture and probably to expand and/or consolidate their ruling, at least in their own lands.

Yeah, that was my thought as well. It could be a situation like England/Scotland where the island is split for centuries between two powers. If the Emishi survive and unify I wonder if the Ainu would be involved at all. They supposedly spoke a very similar language, so the Emishi might have an easier time than OTL Japan incorporating Hokkaido (which might still be called Aynu Mosir ITTL).
 
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