dimensions. The northbound caravans carried the peculiar
variety of pepper called "grains of paradise" from the region later known
as Liberia, gold from the Dahomey district, palm oil from the lower Niger,
and ivory and slaves from far and wide. A small quantity of these various
goods was distributed in southern Europe and the Levant. And in the same
general period Arab dhows began to take slave cargoes from the east coast
of Africa as far south as Mozambique, for distribution in Arabia, Persia
and western India. On these northern and eastern flanks of Guinea where the
Mohammedans operated and where the most vigorous of the African peoples
dwelt, the natives lent ready assistance in catching and buying slaves in
the interior and driving them in coffles to within reach of the Moorish and
Arab traders. Their activities, reaching at length the very center of the
continent, constituted without doubt the most cruel of all branches of the
slave-trade. The routes across the burning Sahara sands in particular came
to be strewn with negro skeletons.[5]

[Footnote 5: Jerome Dowd, "The African Slave Trade," in the _Journal of
Negro History_, II (1917), 1-20.]

This overland trade was as costly as it was tedious. Dealers in Timbuctoo
and other centers of supply must be paid their price; camels must be
procured, many of which died on the journey; guards must be hired to
prevent escapes in the early marches and to repel predatory Bedouins in the
later ones; food supplies must be bought; and allowance must be made for
heavy mortality among the slaves on their terrible trudge over the burning
sands and the chilling mountains. But wherever Mohammedanism prevailed,
which gave particular sanction to slavery as well as to polygamy, the
virtues of the negroes as laborers and as eunuch harem guards were so
highly esteemed that the trade was maintained on a heavy scale almost if
not quite to the present day. The demand of the Turks in the Levant and the
Moors in Spain was met by exportations from the various Barbary ports. Part
of this Mediterranean trade was conducted in Turkish and Moorish vessels,
and part of it in the ships of the Italian cities and Marseilles and
Barcelona. Venice for example had treaties with certain Saracen rulers at
the beginning of the fourteenth century authorizing her merchants not only
to frequent the African ports, but to go in caravans to interior points and
stay at will. The principal commodities procured were i