​This paper discusses commerce in Black African slave who were imported from western Sudan to Morocco in the 19th century. Based on statistics gleaned from previous studies we examine problematics of quantitative approaches to the slave trade phenomenon and arising methodological questions. We also investigate transactional methods in slave markets of Moroccan cities, along with the internal organization and operational mechanisms of these markets, as institutions reflecting the realities and status of slaves, as manifested among Moroccan social groups. Our focus is on the slave trade, not on the varied forms of bondage, servitude and serfdom that “slavery” may gloss. Most societies knew slavery in the above catch-all sense, but not all were party to the slave trade, which generally became outlawed while slavery as such persisted, and persists. We review positions expressed by Moroccan scholars against the slave trade (without their bringing an end to the trade) are reviewed prior to transformations in Moroccan society during the first half of the twentieth century, and the practical disappearance of the phenomenon.