You’ll need an amazing starting leader and a great religion to help you. This means constantly expanding around the Horn of Africa and gaining enough of an economy that you can rival a nation that will most likely have a significant technology lead. You need to be strong enough to fight them.
The reality is the the Mamluks (or sometimes the Ottoman) will destroy you when they decide to venture south into Africa. Why you should play them: Ethiopia is a really engaging but difficult challenge that encourages you to expand aggressively. But Ethiopia is easily a dominant force in the area and are only properly challenged by the Mamluks to the north.
This isn’t saying much, however, as there is only a handful of Coptic nations. On the North-East edge of Africa lies the most powerful Coptic nation in the world (at the default 1444 start date).