The Dahar is a low mountain range oriented on a north-south axis and cuts in two the south of Tunisia. Behind the long escarpment of the mountains, which dominate the eastern coastal plain of Djeffara, is the Dahar, the reverse of the plateau that descends gently to the west and ends up sinking under the dunes of the Garnd Erg oriental. These mountains have given shelter to the Berber populations of the plain in search of refuge in the rocky peaks. They built fortified villages, the ksour, according to a troglodyte habitat adapted to the rigors of the climate. In the regions of Tataouine and Béni Khedache there are about 150 more or less in good condition. There are three types of Ksar: Citadel Ksar, Plain Ksar and Mountain Ksar. There are 3 famous Citadel Ksour: Douiret, Chenini and Guermassa. The Ksour Citadel or Kalâa (fortress) for the oldest ones date back to the 12th century. They occupy the summit of steep hills that dominate the village with troglodyte dwellings and underground oil mills. The Kalâa served as a refuge for the inhabitants of the villages when they were attacked. A Ksar is often installed with a Kalâa for the storage of food stocks and the conservation of valuables of the villagers in Ghorfas (granaries).