Abstract
This contribution aims to provide a long-term environmental perspective of the Sahara as a large-scale geographical area. We will first address the question of the origin of aridity, before dealing with fluctuations in the limits of the Sahara on large scales of time and space, in order to provide comparative maps and identify periods of "bridge" or "barrier" for both fauna and man. The focus will be on the Holocene, and in particular on the African Wet Period. We will present specific areas, notably the northern and southern margins, with their environments and resources, and their role as spaces for the emergence of innovations (domestication, agriculture, pottery-making and metallurgy).
