Military action
Toz splits off from the rest of the Empire, precipitating a series of wars between the two.
After several centuries of cooling relations on the basis of conflicts between noble houses, a revolt to establish an independent Toz leads to that nation achieving its aims after a protracted land and sea war that comes to a stalemate rather than the destruction of either combatant. For the sake of preserving the rest of the empire intact, Khazig cedes its culturally distinct province into a politically independent entity, but bad relations persist and smaller wars and naval conflicts flare up from time to time.