What religion was brought to Africa from Arabia?

According to Arab oral tradition, Islam first came to Africa with Muslim refugees fleeing persecution in the Arab peninsula. This was followed by a military invasion, some seven years after the death of the prophet Mohammed in 639, under the command of the Muslim Arab General, Amr ibn al-Asi.

from the web

Explanation:

so Islam

swahili is an extremely rich and complex civilization, a set of ethnic groups articulated by a language and a series of cultural elements that fuse the african traditions, islam and indian culture. this growth was largely a result of the indian ocean trading network that brought in not just man-made riches, but also religious ideas, specifically islam, which had a significant impact on the local culture. furthermore, the development of the swahili language gave a common cultural unity to the people.