The study of West Africa has contributed to the expansion of comparative arid-lands floodplain prehistory, from both the data collection (cultural and historical) and the theoretical aspects. The neoevolutionary approach that often pictures Africa as a backward continent has been successfully challenged. In the Middle Senegal Valley and in the Inland Niger Delta, research on their societies’ complexity done along these two subcontinent’s floodplains has described new processes (including urbanization) that were not previously featured in the archaeological literature. The two floodplains, because of their ecological diversity, with the richness of their ecological diversity, attracted Saharan populations affected by drought at the end of the second millennium and the first millennium BC. However, after their initiation occupation the two areas took different trajectories in complexity and settlement organization. Large complex settlements have been found at Jenne-jeno and in the Ile a Morphil that illustrate whole new trajectories of civilization. These forms of complexity, found in areas with historically known polities, were not included in the range of possibilities predicted by standard complexity theories regarding civilizational development. Ethnographic and historical data, reveal the existence of societies with a central authority embedded within and balanced by a diffuse, segmented and heterarchical power structure; often as a strategy to resist the individual consolidation of power. These societies exhibit evidence of horizontal differentiation and consensus-based decision making. All these types of organization are characterized by the presence of several sources of power vested in corporate entities, such as lineages, age groups, cults and secret societies.
Political complexity in archaeological research has traditionally been defined as socio-political differentiation (roles, statuses, offices) integrated through centralized systems of power and authority. In recent decades the assumption that complex organizational forms tend to be hierarchical in structure has been called into question, based upon both archaeological research and ethnological observations worldwide, including in classic archaeological case studies of centralization. Moreover, there has been an increasing interest in exploring variability in political legitimizations and articulations of power and authority globally. Until these theoretical shifts, West African complex societies, both archaeological and from ethnographic analyses, were largely ignored in discussions of political complexity since many (but not all) conformed poorly to the expectations of highly centralized power and administration. West African ethnohistoric and archaeological examples are now playing important roles in current discussions of heterarchical organizational structures, checks on exclusionary power, cooperation, urbanism, ethnicity, and the nature of administration in states.