The M'Zab Valley, located within the Sahara, 600 km south of Algiers, is the site of a unique group in a restricted area. Traces of very early settlement are to be found on the plateau and rocky slopes bordering this valley, which has been ravaged by rare and devastating flooding of the wadi. However, systematic occupation of the land and the adaptation of a strikingly original architecture to a semi-desert site date from the beginning of the 11th century and are the achievement of a group of human beings defined by clearly defined religious, social and moral ideals.
The Ibadis, whose doctrine in many ways achieved the intransigent purism of Khridjism, dominated part of the Maghreb during the 10th century. They founded a state whose capital, Tahert, was destroyed by fire in 909; they then sought other territorial bases, first at Sedrata and finally in the M'Zab. The site bears witness, in a most exceptional manner, to the Ibadi culture at its height.
The primary reason for choosing this valley, which until then had been inhabited only sporadically by nomadic groups, was the defensive possibilities that it offered a community that was concerned with its own protection and fiercely dedicated to the preservation of its identity, even at the expense of isolation. The occupation of the land and the organization of space were based on very strict principles and, in their precision and their detail, were exemplary in character. A group of five ksour (ksar: fortified village) - El Atteuf, Bou Noura, Beni Isguen, Melika and Ghardia - located on rocky outcrops housed a sedentary and essentially urban population. Each of these miniature citadels, encircled by walls, is dominated by a mosque, whose minaret functioned as a watchtower. The three unchanging elements - ksar, cemetery, palm grove with its summer citadel - are found in all five villages. They serve to illustrate an example of a traditional human settlement, which is representative of a culture that has continued into the 20th century.
The mosque, with its arsenal and grain stores, was conceived as a fortress, the last bastion of resistance in the event of a siege. Around this building, which is essential to communal life, are houses built in concentric circles right up to the fortress walls. Each house, a cubic cell of standard type, illustrates an egalitarian ideal, whereas in the cemetery only the tombs of sages and the small mosques are distinguished in any way. The pattern of the life in the M'Zab Valley included a seasonal migration. Each summer the population moved to palm groves, where the 'summer cities' were marked by a looser organization, the highly defensive nature of the houses, the presence of watchtowers, and a mosque without a minaret, comparable with those in the cemeteries.
The settlement of the M'Zab Valley has exerted considerable influence on architects and city planners of the 20th century, from Le Corbusier to Pouillon.