the people along the coast a mix of Arabs, settlers from other areas, and berbers. the desert is purely Berber territory. the reason that is so is because the Arabs settled in the cities after they had conquered them. they even founded a few: Qayruwan, in Tunis, and Tunis city itself, are both Arab in origin. they also settled in Lybia, Tunis, morocco, Mauritania, western sahara, and even Spain, siciliy, and malta (hence the language known as maltese). but it is worth pointing out that they were never the majority-just a minority that influenced their neighbors.
as a result, Algerians do speak arabic-allbeit a dialect that is unintelligeable to me (my dialect is a levantine one). and no, you don't have to be from the peninsula. I'm considered an Arab, since I'm descended from Arabs who, if I get my grandparents, settled in northern Iraq, and later Palestine/Israel. they also mentioned that the founder of my family, Zallum, fought in Saladin's Army. there is also a place in Saudi Arabia with that name.
Bookmarks