Someone from the Denianke Dynasty in Senegal. Following Morocco's invasion of Songhai that empire was a shell of itself that imploded. If the Fulo play their cards right, get better access to gunpowder weapons and cavalry (possibly through money from cotton plantations?), then the Sahel is ripe for the taking.
The demographic change would be akin to the Fulani Jihads but 100 years earlier.
I like this one, would be good to see a timeline. Also does the morrocan invasion of songhai count? As didn't Morrocan soldiers continue to rule Timbuktu for a while