Since African Political Systems, edited by Fortes and Evans-Pritchard in 1940, many monographs have been published on particular political organization of pre-colonial Africa. Some attempts have been made to synthesize these data in order to constitute a typology of African political organizations; for instance the segmentary type has been studied in Middleton's Tribes Without Rulers (1958), and the absolute monarchies have been given an important place by Murdock in his Africa (1959) and by others (e.g. P. Hadfield: Traits of Divine Kingship in Africa, London, 1949). Typological research falls within the historian's province if he is interested in the problem of uniformities in history.