African historians have shown little interest in the collection or critical examination of documents which concern population, its distribution or movement. From the example of Senegambia, the authors show that this study of population, using a multi-disciplinary approach, is a prerequisite for the over-all history of social formations. Sources are rarely those of classical demographic history but are, above ail, unconventional ones. Yet thèse allow the coverage of various periods and the treatment of important démographie themes which require true statistical data, bearing in mind the limits inherent in the available evidence. However, in underlining recent developments in knowledge of the pre- and proto-historic periods, pre-colonial and colonial, the authors show that the understanding of the past of African populations is not confined to a few statistics and can be greatly increased by the use of all the sources which are still accessible. Two annexes are devoted to the earliest administrative censuses and demographic inquiries and also to the division by sex in thèse documents.