Why is much of Mauritania dry and sparsely populated?

Mauritania is largely arid and sparsely populated primarily due to its harsh climate and challenging physical geography. The country’s aridity is driven by persistent northeastern trade winds and the harmattan, a hot, dry wind that exacerbates the lack of moisture. Precipitation is minimal and decreases significantly from the south to the north, leaving much of the interior as vast desert peneplains and sand-covered regions.12

The landscape is dominated by skeletal soils, regs (pebble-covered plains), and dunes, which cover about half of the country, making large areas unsuitable for agriculture or dense settlement. Consequently, more than nine-tenths of the population is concentrated in the southernmost quarter of the country, where the Sahel region provides more favorable conditions for stock raising and agriculture. While historical nomadic life once allowed populations to traverse these arid zones in search of water and pasturage, modern urbanization has shifted settlement patterns toward urban centers and areas along transportation arteries.345