1510s

Scholarly analysis of early Atlantic slave voyages indicates that mortality during the Middle Passage in the early sixteenth century ranged from roughly 15 to 25 percent of captives per voyage, driven by dysentery, dehydration, scurvy, smallpox, and the brutal conditions of confinement. Enslaved people were chained in spaces as small as 18 inches high for voyages lasting six to fourteen weeks. Those who died were thrown overboard. These death rates declined somewhat in later centuries as traders sought to protect their 'investment,' but remained catastrophically high throughout the trade's history.

Holy Roman Emperor Charles V (King of Spain) granted the first formal asiento — an exclusive contract — authorizing the direct shipment of 4,000 enslaved Africans annually to the Spanish Caribbean colonies, bypassing the previous requirement that enslaved people be 'seasoned' in Spain first. This bureaucratic innovation massively accelerated the slave trade and established the asiento system that would govern the trade for over two centuries, later fought over by European powers as a source of enormous profit.

Following the Spanish settlement of Cuba, enslaved Africans were transported to the island beginning around 1513 to labor in gold mining and agricultural production. The Spanish government issued licenses (asientos) controlling the trade. Cuba's plantation economy would eventually make it one of the largest recipients of enslaved Africans in the entire Atlantic trade, with over 800,000 people imported over the following centuries.

Hernán Cortés brought enslaved Africans with him on his conquest of Mexico beginning in 1519. Among them were both enslaved laborers and free Black participants like Juan Garrido. As the conquest proceeded and indigenous populations collapsed under disease and violence, demand for enslaved African labor in New Spain (Mexico) rapidly grew. Mexico became a significant destination for the Atlantic slave trade, with an estimated 200,000 Africans imported over the colonial period.

Juan Garrido, a free Black man of West African origin, accompanied Juan Ponce de León on his expedition to Florida in 1513 and later joined Hernán Cortés in the conquest of Mexico (1519–1521). He is documented as the first person of African descent to set foot on the North American mainland. His presence illustrates the complex status of some Africans in early Spanish expeditions — simultaneously participants in colonialism and racialized figures within a system that enslaved their kin.