This comes up a lot. As in "what happened to...?
Before the Great War of 2077 the world was running out of Oil, Uranium and other natural resources. Europe broke down into warring nations states after they teamed up to attack the Middle East. The European Union and the United Nations fell apart.
The Great War was a global nuclear war aka World War III. Which means Africa was involved, if only in its destruction from other world powers. We know the whole world was involved in the Great War (which only lasted two hours) from the intros of Fallout, Fallout 2 and Fallout 3, we could even include Tactics.
Africa was still for the most part pawns to European powers in the 1950s. Given the timeline split happened sometime, after World War 2, or in the 1950s and things remained in the 1950s mindset. It is safe to say IMO that Africa was still divided up between European Powers.
If not we still know Africa is the second larges continent in the world and is very rich in resources. We see in our timeline (Today) that China is all over Africa getting as many much as it can resource wise. It isn't alone. The USSR was still around in the Fallout Universe by the time of the Great War. We know the USSR was very active in Africa during the Cold War. In a world starving for resources Africa would be divided up drained for all it is worth by the worlds powers. It would also mean those resources can't be allowed to fall into the hands of your enemy in the event of a nuclear war so they need to be destroyed.