As the hoards of abominations swept over the land and throughout the seas, the few remaining Blue Wizards sacrificed themselves in The Undertaking. To turn their very souls into sanctuary. Each becoming an impenetrable sphere a hundred leagues across. Nothing can pass in, out, through, beyond. Inside each sphere are saved remnants of the people who once were. Each group planting, sowing, living and dying as best they can in isolation.
Ages have passed.
The Undertaking spell is failing.
The Wall is coming down and we are ill prepared.