This is a difficult thing to describe for any pre-modern polity, where vassalage and weak frontiers make it difficult to describe if a central power actually co

This is a difficult thing to describe for any pre-modern polity, where vassalage and weak frontiers make it difficult to describe if a central power actually controlled a territory. The Ottoman Empire de-facto exercised little control its North African vassals, the Roman Empire had increasingly weak control over its frontiers due to migrations and incursions, etc.