Dromedary Caravan in the Dunes near Nouakchott, Mauritania In this country on the edge of the Sahara - the world's largest sand desert, covering 3 million square miles (7.8 million km2) - dromedaries, animals adapted to the extreme local conditions, make up an important part of the domestic livestock. Mauritania, which is 90 percent desert, is particularly vulnerable to the consequences of human actions on the environment. The circumference of these great dunes often feature vegetation that is naturally adapted to the aridity, particularly in proximity to the slightly less arid regions where people live.