Grand Erg Oriental follow the wind's direction. There are other types of dunes, as well as "complex" dunes. Saharan winds are also known to clear an area of sand altogether, leaving bare rock (hamada) or gravel (reg). The "Grand Erg Oriental" is accessible overland by an Algerian road, which goes south from Constantine. It passes through the Aurès mountains, then salt lakes by the city of Biskra. Next the road skirts the western edge of the erg. After about 500 km. in all, it reaches the ancient oasis of Ourgla [Wargla]. Since late antiquity Wargla was a stop for the Saharan trade, being
What Is a Nation? Language, by contrast, "invites us but does not force us, to unite". Countries which share the Spanish or English language don't merge with one another, while the people of Switzerland speak several languages. Modern nationhood also cannot be based on religion, which Renan observes, is currently practiced according to individual belief. "You can be French, English, German, yet Catholic, Protestant, Jewish, or practicing no religion". Mutuality of interests is fine for corporations and their affiliates, but nationality is based on sentiment. Geography merely leads us astray, and often to violence: "Mountains don't know how to carve out countries". Renan concludes