Erg (landform) and western Asia, and Central Australia. In South America, ergs are limited by the Andes Mountains, but they do contain extremely large dunes in coastal Peru and northwestern Argentina. They are also found in several parts of the northeast coast of Brazil. The only active erg in North America is in the Gran Desierto de Altar () that extends from the Sonoran Desert in the northwestern Mexican state of Sonora to the Yuma Desert of Arizona and the Algodones Dunes of southeastern California. An erg that has been fixed by vegetation forms the Nebraska Sandhills (). Sand seas and dune
Erg of Bilma been stabilized by the growth of vegetation, allowing human cultivation of crops like millet and sorghum on the slopes. The ancient Bornu Empire to Fezzan caravan routes had to cross the dunes of the erg south of Bilma as the last major obstacle before reaching the sahel. While that traffic largely ceased after 1820, trade though the erg of Bilma continues from the Lake Chad region and the Termit Massif on a small scale. Erg of Bilma The Erg of Bilma is a dune sea (Arabic: "erg") in the Ténéré desert region of the south central Sahara Desert. The Erg