Some of these were Moorish Berbers, some negroes, but most were probably Jolofs from the Senegal, a warlike people of mixed ancestry.

Raiding in the Jolof country proved so hazardous that from about 1454 the Portuguese began to supplement their original methods by planting "factories" on the coast where slaves from the interior were bought from their native captors and owners who had brought them down in caravans and canoes.

Thus not only was missionary zeal eclipsed but the desire of conquest likewise, and the spirit of exploration erelong partly subdued, by commercial greed.

By the time of Prince Henry's death in 1460 Portugal was importing seven or eight hundred negro slaves each year.

From this time forward the traffic was conducted by a succession of companies and individual grantees, to whom the government gave the exclusive right for short terms of years in consideration of money payments and pledges of adding specified measures of exploration.