Why did early North African settlements often develop in plains and valleys near the mountains?

Early North African settlements often developed in the plains and valleys near the mountains primarily because the dense forests covering the mountain slopes were intractable and difficult to inhabit.1

While the mountains received the highest levels of precipitation in the region, the rugged terrain and thick vegetation made them less suitable for early settlement compared to the more accessible plains and valleys located between or south of the mountain ranges. Additionally, the rivers flowing from the mountains often deposited silt at the foot of these ranges, creating fertile areas that were more conducive to settlement than the dense, mountainous interior.12