Why did Arab geographers call the Caucasus the “Mountain of Languages”?

Arab geographers referred to the Caucasus as Jabal Al-Alsun, or the "Mountain of Languages," because the region has been known since antiquity for its extraordinary linguistic diversity and the large number of distinct languages spoken within its relatively small territory.12

This concentration of languages is a result of the region's complex history. Throughout the centuries, the Caucasus has served as a crossroads for migrating peoples and a buffer zone between rival empires. Under pressure from stronger neighbors, many individual ethnic groups took refuge in the isolated ravines of the mountain ranges, which allowed them to preserve their unique cultures and languages over time. Today, more than 50 different peoples inhabit the region, speaking a variety of tongues that include Indo-European, Turkic, and the indigenous Caucasian languages.341