I'm from Tunisia which is one of the areas where berbers used to rule. and i have to say, even we don't know much about them. we have some landmarks and writings ( and some people still speak the berber language) but we don't know details of their lives. When the arabs came it was a conquest, some areas just gave up , some fought and eventually lost. Also a reason why we don't know much about them is because the orthodox line of islam always tries to make islam the only player in the region, or the only component of a people's cultural heritage. and that backfired to the religion by not allowing it to transcend the middle-ages frame of mind, and it caused national identity problems in many regions