Over a thousand years ago, the Soga Clan defeated the Mikaboshi, who were a clan of sorcerers. So to follow that, it is likely the Mikaboshi went on to become the people of Shokoku. Though they are more than likely aided by the Datenseki. Which is how the Shokoku came back to having power.
Of course, when a nation that was once powerless has power, they will have their own demands. Which is where it gets dissolved, and the war that we heard about is imminent.
