Islam spreads inland, and by 1400 a big-ass Islamic state emerges in what is central Nigeria. Uniting by religion tribes of savanna and jungle, the Sultanate (later Caliphate) of the lower Niger has the biological and immunilogical package to survive a March to the Southeast, and the Caliphate spends a busy 500 years doing a Reverse Draka converting the backwards heathens of southern and central Africa to Islam by Fire and the Sword, eventually hooking up with the Swahili on the east coast. Then the time comes to liberate their pasty-skinned co-religionists to the north from the oppressive yoke of Firanji rule...
This. Such a state would be near-impossible to maintain even using modern technology, and going back into the past, Africa's large geographic size makes it an impossible place for a large state to be, especially as many areas are unsuitable for the horse. In addition to this, there are also huge cultural differences, etc...I honestly think that people need to respect that some things are impossible. Africa is larger than all of North America, which here includes both Greenland and everything you'd otherwise classify as Central America. Moreover, large parts of it is desolate, disease-ridden, or otherwise a large administrative strain. It simply isn't going to work without ASB interfering.
EDIT:
And how, exactly, would this state emerge, get the resources to conquer such a territory, and manage to stay together for five centuries?
If even the United States could not unify North America from Alaska to the Isthmus of Panama, then Africa is even harder.
This. Such a state would be near-impossible to maintain even using modern technology, ...
I'm skeptical of that statement - China has more people than all of Africa, and the USSR+Mongolia and Eastern Europe was almost as large in terms of area.
(Admittedly, it's a wee bit harder in a pre-modern era. That was just a tossaway TL there)
Bruce
USSR+Mongolia and Eastern Europe was almost as large in terms of area.