While the Atlantic trade was being suppressed, the desert routes remained active and in some decades expanded. Slaving states of the central Sudan such as Sokoto and Bornu, and the Nilotic raiding frontier in Darfur and the Bahr al-Ghazal, supplied captives who were marched north to Fezzan, Ghadames, Ghat and Tripoli, to Morocco, and along the Forty Days Road to Egypt, for sale into domestic service, concubinage, military slavery and agricultural labour in North Africa and the Ottoman lands. Women and children predominated, in contrast to the Atlantic trade, and castration for the eunuch market was practised at a small number of centres with very high mortality. Ottoman prohibitions from the 1850s, French and British pressure on the Saharan termini, and eventually colonial occupation of the Sahel reduced the traffic, but caravans were still being intercepted at the end of the century and slavery persisted in law in parts of the region into the twentieth. Volume estimates rest on entrepot records and travellers' counts, not on registers of any kind.
Saharan and Sahelian states, merchant networks and raiding polities carried enslaved people north across the desert to North African and Ottoman markets
Ralph Austen's estimates, the standard series, are built from caravan and market records at the North African and Ottoman end rather than from any count of the raided populations, which spanned Bornu, Hausaland, Darfur, Wadai and the Nile Sudan. There is no census of these polities in this period and no defensible aggregate to divide by.
No death toll can be established. Mortality on the desert crossings was high - contemporary European travellers described caravan routes marked by remains - and mortality among boys castrated for the eunuch trade was extreme, but there are no records from which a figure could be built. Deaths in the raiding wars that supplied the caravans are equally unquantified.
The African Economic History Network survey and the syntheses of Austen, Lovejoy and Toledano on which it draws document the taking of captives in raids, the predominance of women and children destined for domestic service and concubinage, and the practice of castration for the eunuch market.
Mali, Niger, Libya, Morocco, Chad, Egypt