Many geographers have seen the Maghreb in terms of two major domains-a Mediterranean domain (tell) limited in extent and alone favourable for agriculture and sedentary life, and beyond, a vast steppe domain (sahara), antechamber of the desert, the home of pastoral nomadism. This approach closely reflects a European evaluation of the possibilities which the region offers for human settlement. However, the concept of tell and sahara has been used to explain many aspects of the social, economic and political evolution of the region, even though, over the centuries, the Maghreb has been conquered by divers invaders who each viewed the environmental possibilities in terms of their own past heritage, present situation and future expectations. The result has been a distorted picture of the region before the French occupation. With the decline of pastoral nomadism and the rapid urbanization which has taken place during the twentieth century, the opposition of tell and sahara, of cultivator and pastoral nomad, is no longer meaningful for the inhabitants of an independent Maghreb. A new approach to the geographical study of the region is demanded. THE Maghreb, it has been said,' is a marchland where the structural and climatic influences belonging to the Mediterranean realm engage in a struggle with the rigidity and aridity of the desert. In modern times the indigenous inhabitants themselves have been acutely aware of these two forces acting upon the region. The Algerians in particular have long distinguished between the Mediterranean coastal zone known as tell, with its heavy, wellwatered soils permitting cereal cultivation and arboriculture without irrigation, and the lands beyond known simply as sahara, where parched, sandy soils give unreliable harvests. For French geographers writing on the Maghreb, the concept of tell and sahara has become a central and ever-recurring theme, and it has been employed to explain many aspects of the social, economic and political evolution of the region. One such writer, Jean Despois, in a book L'Afrique du Nord first published in I949, draws attention to the fact that the limited extent of the tell or Mediterranean domain (Fig. i) and the extension of Saharan conditions into the vast steppe domain which borders it to the south has been of fundamental importance. It has given the nomads a dominant role in the history of the Maghreb and one result, he maintains, has been centuries of political instability and lack of unity. Agriculture and sedentary life-the essential economic base for stable political units-is only possible in the Mediterranean domain which is reduced to a relatively narrow band, especially in the central Maghreb. In the steppe beyond, the nomadic tribes, generally opposed to and often in conflict with the central authorities, have, over the centuries, successfully prevented the persistence of large, stable states. Another result of the close juxtaposition of Mediterranean and steppe domains has been the south-to-north orientation of tribal movements and of commercial exchanges, which have not favoured contacts between the eastern and western parts of the Maghreb.