The correct answer to this open question is the following.
Historians think that Islam arrived in Africa due to the persecution of Muslim people that traveled to the African continent. Years later Caliphates ordered the invasion of African territories. General Amr ibn al-Asi was one of the military officers that led the Muslim troops into African territory It all started in North Africa. Then, trade had too much to do with the expansion of Islam from the North and West Africa, to the Eastern side. Although Islam became the prominent religion in many parts of Africa, Muslim people showed tolerance to other religious beliefs.