The region never recovered post-Carthage. I live here, so if you are talking about a powerful civilization, then there is only Carthage. After that it was mostly trading cities going through boom-bust which are setup by other civilizations (Rome/Byzantium/Caliphates/Ottoman...)

> These cities were conquered. Some were sacked and destroyed. There was major loss of life, economic destruction, and loss of property, including written works. The conquerors, at the time, did not much appreciate the value of what they were destroying.

It's just life. North Africa was just a bunch of tribes/cities. It is easier for an invader to tackle them one city at a time than taking a full united civilization.