I have long been fascinated by the Muslim brotherhoods of Senegal. Nothing on the same scale exists in The Gambia - in Senegal everyone is a member of one of the brotherhoods, and swears allegiance to one of the Serigne. Every year the brotherhoods hold large Gamos, huge gatherings where all members convene and Allah is praised, and speeches/lectures are given by the Serignes. When a Serigne dies he is replaced by the next male heir in line. Serignes wield great power, perhaps even greater than the President: theirs is a religious rather than political rule, and therefore more enduring - it is lifelong, and not at all open to any form of challenge, as the Presidency (a democratic position) is.
People over here join one of the Senegalese brotherhoods, and cross over into Senegal to attend annual Gamos and visits to pay homage to their Serignes. Mourides all over the world work hard and send back money every year to Touba. It is a disciplined, hard-working order (for the sci-fi buffs: it brings to mind the Fremen of Frank Herbert's Dune sequence of novels, and Mu'addib, their messiah).
Mouridisme and all the other brotherhoods build up on the foundation of Islam - they are extensions rather than completely different religions. I think it's fair to say though that quite a few Mourides respect and revere - or feel more of a connection with - Serigne Touba than the Prophet himself (I use Mouridisme as an example because it is the one brotherhood whose adherents walk closest to the thin line separating acceptable Islamic practice from blasphemy - I have heard Mourides compare Touba to Mecca, and Serigne Touba to God, drawing horrified gasps and "Asta-furrlah"s from my Tijan grandmother). So all the brotherhoods work within the frameworks of Islam. But what would have happened if Islam hadn't made its way to us in the first place? Would Serigne Touba, for example, then be free to start his own religion?(Discouraging the starting of new religions is on of the things monotheistic religions are especially good at: in Islam for example worship of false Gods is one of the worst crimes you can commit). Perhaps, if things had gone differently, if Africa did not occupy the position at the bottom of the stack which it does now, importing religion and culture and language, the story of world religion would be different, with African religions being spread all over the world, an African messiah being worshipped and expected to come back to herald the coming of the end times. An African God - gods? - watching over us as we went about our daily lives.