Colonial boundaries became redefined as the borders of new nation states, even where those boundaries were arbitrary or, in some cases, pernicious. The best known example is in Rwanda, where two very different tribes, the Hutu and the Tutsis, were combined into one nation. But more generally, the colonizers' focus on value extraction really hurt these new nations. Europeans claimed to bring civilization and economic development to their colonies, but this economic development focused solely on building infrastructure to get resources and export them. Now, whether European powers deliberately sabotaged development in Africa is a hot-button topic we're going to stay well away from, but this much is inarguably true. When the Europeans left, African nations did not have the institutions necessary to thrive in the post-war industrial world. They had very few schools, for instance, and even fewer universities.