I would agree that perhaps you couldn't tell today which is natural tribal warfare and which is Muslim influenced, but I think tribes were killing each other well before Muslims existed.
I don't think Islam was the birth of tribal warfare in Africa at all, I think it was just an branch from original tribal warfare.
I do agree with you that today they are like a cancer causing lots of issues.
It was from the beginnings of the Muhammadan crusades a goal of the Caliphate to take over the entire African continent.
But due to the difficulties encountered in India, they never managed to reach very far into the south Africa's. Then there were the counter attacks of the Crusades to retake the holy lands from the Mohammedans, and finally a severe pummeling from Genghis Khan that halted much of the Muhammadan crusades.
Then the Ottoman empire grew, but never pushed deep into south Africa either, so in that sense, any tribal warfare in the south wouldn't have been much to do with Muslims.
Even the Northern Africa's drifted away from hard line Islam-ism, and became a blend of tribal African customs and Islam, and of course the Christianity brought by the missonary efforts of a few centuries, which today (the better part of this past half century) is what the Arabs are trying to purge, and convert them into Wahabbi style of Islam.