They weren’t countries. They became countries when the colonizers (and I’m using that term as accurately as possible) lumped together into managed regions and then told them they were countries with their own governments and flags. It was all “We’re going to conquer these people and these people and these people, then put Governor Fitzroy, nephew to the Prince, in charge of all of it with a big army to back him up.” Then they wrote laws and made flags and all the happy crappy stuff they do. Then they lost WWII (because pretty much everyone except for the US lost WWII), and said “you’re on your own.”

They turned former colonies into artificial countries with governments that all but guaranteed factionalism.

There was always war, and there always will be war. But the specific type of war we’re seeing in former colonies is because of the post-colonial situation.