"A barbarous people who live in isolation of one another" is this a true assessment of the people of North and West Africa.
Berbers communities were conservatives and maintained their locations in isolations which they maintained when the invaders advanced in west Africa. The invasion began by the Phoenicians (1000 BC) and during 146 BC, the Romans. Berbers became more geographical isolated but series of invasions from other groups such as Vandals, Byzantines, in the 17th Century, Arabs invaded their lands. Berbers took refuge to the mountainous regions of southern Tunisia server as their maintained isolation regions.
The isolation of the Berbers does not explain the true assessment to describe the nature of settlement of the people of North Africa and West Africa as most tribes in these regions interact and integrate with each other over the boundaries.