Islam came to Africa through trade which had already been established in East Africa from the Arabian peninsula by 400CE. Eventually, Islam spread all over the entire African continent. Islam reached parts of North Africa in the 600s CE and 700s CE.
Most in the North converted to Islam but still, some remain Christian such as Kush and Egypt.
It was said by some (incorrect) historians that they came from the Southeastern part of Africa first, but this is false. They came towards the northern-middle east according to the map. I hope this helps you :)
