I had a nice lengthy response to the PnP thread, but it's gone now.
Not sure about the muslim stuff in Somalia and the Horn of Africa, but as far as the rest goes;
Europe figuratively, and probably literally, raped the shit out of Africa. The turn of the 19th century Africa wasn't too shitty-a-place, but Europe had a bit of a jump on them. So, to keep the colonization going they decided to romp around Africa, taking and claiming what they wanted, with complete disregard to already set tribal boundaries. Because they were a bit more advanced they could just kick the shit out of a lot of people, although there were some exceptions like the Zulu warriors kicking the absolute shit out of a huge group of British who underestimated them, not sure what they name of the battle was, somewhere in South Africa. Towards the end of the 19th century European nations held the Berlin Conference, where they pretty much divided all of Africa according to this, without any African consent, basically like saying to each other "You take this, I take that". The Belgians ended up with what is today the Democratic Republic of the Congo, where King Leopold upheld ridiculous practices. If you didn't harvest enough of some shit, you're arm got cut off. Basically, we were a bit unfair to them.