May I take a moment to point out that this is merely one of the areas of modern concern that can be traced back to the British? Sikes-Picot, India/Pakistan, Myanmar/Burma, Ireland/Northern Ireland? And don't get me started on those colonies they lost in the late 18th century. What a disaster that has turned out to be.
****

This was all done by design. The entities you cite - killed each other and cost each other money and resources decades after the Empires left.

It was another gift to the world from Europe and they were able to exploit internal tribalism, or exploit internal differences and turn it into tribalism combined with buying off the well educated or well to do.

Luckily, this will NEVER happen to America. No foreign country can exploit the Red vs Blue thing. Or try to concentrate an ethnic vote in a certain region to influence politics.

Oh, wait......