Erg Chebbi is one of Morocco’s several ergs – large seas of dunes formed by wind-blown sand.
In places, the dunes of Erg Chebbi rise up to 150 meters from the surrounding hamada (rocky desert) and altogether it spans an area of 28 kilometers from north to south and up to 5–7 kilometers from east to west lining the Algerian border.
The nearest sizable town is Erfoud, about 60 kilometers further north. One other city is Rissani, around 40 kilometers from Merzouga. Rissani which became prosperous from the 8th to the 14th century due to its control of the caravan routes.