How did Arab nomad migrations affect Berber settlement in the plains and mountains?

Beginning in the 11th century, an influx of warrior Arab nomads from the east significantly altered the demographic and settlement patterns of North Africa. These migrations exerted pressure on the indigenous Berber populations, effectively driving them off the plains and into the mountains, while the nomads overran the desert regions.1

This displacement was a key factor in the broader process of Arabization, which gradually reduced the prevalence of Amazigh languages and contributed to the loss of original Berber identities as populations shifted toward speaking Arabic. By the early 20th century, the Berber world had been largely reduced to isolated enclaves, primarily situated in mountainous ranges such as the Aurès and Kabylie in Algeria, and the Rif, Middle Atlas, and High Atlas in Morocco.1