Answer:
Islam spread through trade.
Step-by-step explanation:
The fastest way that Islam developed was thanks to Islamic traders. After conquering Africa, Islam spread over the continent through merchants, teachers and missionaries and all of it was peacefully. This way Islam spreaded over Sahara. There are researcher that claim that some countries accepted Islam without merchants, they accepted it as a religion. However, in Ghana, kings haven’t converted into Islam, they rather just tolerated the merchants and those who wanted to convert.