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
Liwa (Arabic) Liwa (Arabic) Liwa, or Liwā’ (), is an Arabic term meaning ensign, or banner. The word has developed various other meanings in Arabic: "Liwa" was used interchangeably with the Turkish term "Sanjak" in the time of the Ottoman Empire. After the fall of the empire, the term was used in the Arab countries formerly under Ottoman rule. It was gradually replaced by other terms like qadaa and mintaqa and is now defunct. It is only used occasionally in Syria to refer to the Hatay Province, ceded by the French mandate of Syria to Turkey in 1939, at which time was