I would argue that most intra-national strife comes from histories of wars and blood feuds. The Balkans being a case of this. > And if their cultures clash wit

I would argue that most intra-national strife comes from histories of wars and blood feuds. The Balkans being a case of this. > And if their cultures clash with each other, you have a recipe for enduring intra-national strife. Feels logical but also feels unproven.