The need for medieval states or polities to collect and distribute resources to maintain armies affected all aspects of political organization and processes, determining fiscal systems and methods of extracting surplus. It impacted directly upon political structures as well as upon the structures and memberships of political elites and, according to region and period, regional cultures and social life. But logistical infrastructures which evolved in different parts of the medieval world from the later Roman empire until the twelfth century are subjects which remain almost entirely neglected: road-systems, communications in general, and the supportive capacity of lands in which armies were based or through which they passed; issues of relative availability of resources, including relationships between sizes of populations, levels of agrarian and other production, and the size of armies and their supporting structures within and between medieval societies. Virtually no research has been carried out to place the social logistics of the medieval Byzantine and Islamic worlds within the broader comparative context which they clearly need if the directions and tendencies of their different development is to be understood properly. Although several of these aspects have occasionally been subject to scholarly attention, they have also been the subject of unproven assumptions rarely tested against evidence.