The impact of a changing environment on human society and, conversely, the impact of man’s activities upon the environment are important and contentious subjects today. Climatic and environmental change have also been credited with bringing about major shifts in human history. One such case is that of the decline of Roman North Africa and its conquest by the Arabs. The evidence for this process is, however, far from clear-cut, and Professor Shaw’s concern in these studies is firstly to re-examine what is known, from both archaeological and written sources, and how it has been interpreted, work which has led to some substantial revisions of accepted accounts. In the final three articles he turns to analyse how Roman society functioned on the edge of the desert and, in particular, to investigate the careful exploitation and control of critical water resources.