Erg Chebbi (Arabic: عرق الشبي‎) is one of Morocco's two Saharan ergs – large seas of dunes formed by wind-blown sand. The other is Erg Chigaga near M'hamid. The dunes of Erg Chebbi reach a height of up to 150 meters in places and altogether spans an area of 50 kilometers from north to south and up to 5-10 kilometers from east to west lining the Algerian border.