You imagine Arabs were always were they are? Or any race for that matter? Dear oh dear. The migration of phenotypical Arabs into Africa is a process that is still ongoing. Or do you imagine Tunisia, Morrocco and Libya always had populations that looked like that? Oh dear.

Ancient Egypt, early Egypt was undeniable African. Precursors of what would become Egyptian culture are found far to the south for one small example. Only during LATE Egypt did the Persians followed by the Greeks, Romans and Arabs carry out successive raids on what was Egypt. The Persians and Greeks both adopted Egyptian superficialities of culture while there which clouds the issue somewhat. Dude... Mohammad was around in 600AD. Egypt was around for a good few millenia before that .