Africa is rife with conflict due to colonial borders. In fact most parts of the world.
Discussion
I’m not sure if that’s true
How?
It's literally always happening.
Ukraine, Azerbaijan, Palestine, Sahara, Guyana, Taiwan, Sudan, Ethiopia, Iraq, Afghanistan, Khasmir.
Berlin Wall, Soviet Union collapse.
Borders, or the construct of them, is what has sperated people, tribes and cultures for centuries.
I know they separated people, but I’m not sure how it caused the poor outcomes of the cultures you just listed. What about the prosperous countries that have borders?