Much of what appears on the present topic in even the most recent general works on Africa is seriously misconceived or inaccurate. The most important study is C. Verlinden, L ’esclavage dans VEurope médiévale, i: Péninsule ibérique. France (Bruges, 1955), together with the many other studies and articles by the same author, whose work, however, is not entirely reliable. The present paper goes far beyond Verlinden in its analysis of developments between about 1430 and 1460, the essential source for that period being Gomes Eannes de Zurara, Chronique de Guinée, trans. and ed. L. Bourdon et al. (Dakar, 1960). The best general work on the background is V. Magalhâes Godinho, A economia dos descobrimentos henriquinos (Lisbon, 1962); for the African side, R. Mauny, Tableau géographique de l ’Ouest africain au moyen âge (Dakar, 1961). P. d’Azevedo, “Os escravos”, Archivo historicoportuguez, i (1903) and E. Correia Lopes, A escravatura: subsidiospara su histôria (Lisbon, 1944) provide useful material in unsatisfactory studies; see now the excellent guide, A. Ryder, Materials for West African History in the Archives of Portugal (London, 1965).