How did Islam affect northern and eastern Africa?
By conversion and conquest, Islam spreadIslam spread
The spread of Islam spans about 1,400 years. Muslim conquests following Muhammad's death led to the creation of the caliphates, occupying a vast geographical area; conversion to Islam was boosted by Arab Muslim forces conquering vast territories and building imperial structures over time.
https://en.wikipedia.org › wiki › Spread_of_Islam
across North Africa, into the eastern Horn of Africa, and even over the SAHARA DESERT into West Africa.