Iberian Roots of the Transatlantic Slave Trade, 1440–1640

by David Wheat

 “Taboas geraes de toda a navegação” by João Teixeira Albernaz, 1630. (LOC Maps)In its broadest sense, African American history predates the history of the United States, colonial or otherwise; by the time the English colony of Virginia was founded in 1607, Africans and people of African descent had already been present in the Americas for more than a century. Recent estimates suggest that by 1625, approximately 475,000 enslaved Africans had been involuntarily transported to the Spanish Americas and Brazil—more than the number of Africans who disembarked in British North America and the United States during the course of the entire transatlantic slave trade. Though most research on Africans’ involuntary migration to the Americas focuses on the eighteenth and nineteenth centuries, the roots of the transatlantic slave trade are much deeper, stretching back to Iberia (Spain and Portugal), Atlantic Africa, and Latin America during the fifteenth and sixteenth centuries.

By 1430, Iberian expansion in the Atlantic was well under way with efforts to colonize Madeira, the Canary Islands, and the Azores. Over the following half century, Portuguese seafarers gradually explored southwards along Africa’s western coast, rounding the Cape of Good Hope in 1488. In western Africa, Spanish ships arrived soon after the Portuguese, leading to competition between the Iberian powers until formal negotiations at the close of the fifteenth century prohibited Spanish exploration and commerce south of the Sahara.

Following their “discovery” of African populations willing to trade valuable commodities such as gold, ivory, wax, peppers, and grain—and slaves—the Portuguese established trading factories (feitorias) at strategic locations. Some of these outposts were eventually fortified, but unless they had been built on an uninhabited island, their maintenance depended heavily on the goodwill and tolerance of neighboring African societies. Thus while Portuguese activities in some regions were mainly limited to missions of diplomacy and evangelization, major trading factories and bulking centers were established in Arguin, the Cape Verde Islands, Elmina, and São Tomé. Fueled by commerce with multiple polities on the African mainland, and the local production of commodities such as textiles, sugar, and cotton, several of these outposts rapidly became Portuguese colonies peopled by Iberians and increasingly, mixed-race Luso-Africans.

Unlike other areas of western Europe, slavery played a significant role in Iberian society at the dawn of the early modern era. In Lisbon and Évora, and throughout much of southern Portugal, slaves comprised roughly 10 percent of the population by the mid-1550s. A comparable scenario existed in parts of southern Spain; 44,000 slaves made up nearly 10 percent of the population of the entire archbishopric of Seville in 1565. Rural slave labor in Iberia during the fifteenth and sixteenth centuries mainly involved herding livestock, guarding fields and flocks, clearing land, and harvesting and processing crops. Enslaved people also commonly worked as sailors and boatmen on small vessels designed for coastal trade and river traffic. In urban areas, slaves performed a wide range of occupations, laboring as artisans and apprentices, domestic servants, stevedores and porters, construction workers, and street vendors.

In early modern Iberia, slavery was not exclusively associated with racial categories as it would be in the colonial Americas. All available sources indicate that sub-Saharan Africans and their descendants—often referred to as “blacks”—constituted a significant segment of Iberia’s slave populations during the fifteenth and sixteenth centuries. One recent study suggests that as many as 350,000 to 400,000 African captives may have been transported to Spain and Portugal during the two centuries from 1440 to 1640. However, during the era in question, one’s religious background, political loyalties, and geographical origins also played key roles in determining who was eligible to be enslaved. Many enslaved women and men in Iberia were Muslims born in North Africa or the eastern Mediterranean, either captured abroad or purchased as slaves in foreign or local markets. Alongside these moros (“Moors”) and berberiscos were Iberians of Muslim ancestry known as moriscos. Though some enslaved Muslims and moriscos were black, or of mixed racial background, many were described as “white slaves.” Iberia’s slave population also included smaller numbers of captives brought from India and China, as well as native Canary Islanders and indigenous peoples from the Americas.

Given the prominence of sub-Saharan Africans among other ethnic minorities in early modern Spain and Portugal, and the significant role of slavery in fifteenth- and sixteenth-century Iberian society, it should come as no surprise that Africans and people of African descent participated in Iberian efforts to colonize the Americas from the very beginning. Spanish colonization in the Americas began shortly after Columbus’s initial voyage to the Caribbean in 1492–1493. During his fourth voyage to the region a decade later, the crew of one of Columbus’s ships included a black cabin boy named Diego. In similar fashion, the Portuguese became interested in Brazil after Cabral’s voyage in 1500–1501. When Cabral first landed in Brazil, he sent a black sailor ashore to attempt to communicate with indigenous people. During the 1510s, Portuguese vessels trading for brazilwood along the Brazilian coast likewise employed small numbers of black mariners, both free and enslaved.

Though North African, eastern Mediterranean, and morisco slaves were common in Iberia, the Spanish Crown repeatedly prohibited their transportation to the Americas for fear of spreading Islam to the fledgling colonies. Conversely, by the close of the 1530s, black slaves had accompanied Spanish expeditions of exploration and conquest throughout the Americas. Well-known “conquistadors” such as Juan Ponce de León, Hernán Cortés, Pedro de Alvarado, Lucas Vázquez de Ayllón, Hernando de Soto, Francisco Pizarro and others all relied on enslaved black auxiliaries to transport heavy burdens and herd livestock. In some instances, armed black slaves and free people of color are known to have fought alongside Spanish forces—the most famous example being the “black conquistador” Juan Garrido, an African-born former slave who participated in the conquests of Puerto Rico, Cuba, and Mexico, and the exploration of Florida.

Within the first few decades of contact with Iberians and Africans, Native populations declined throughout the Americas, most drastically in the Caribbean. In response, the Spanish Crown instituted policies designed to protect Amerindians from mistreatment and enslavement, most notably the “New Laws” of 1542, and the new repartimiento (labor distribution) system instituted in 1549. Though some loopholes remained, and the exploitation of indigenous peoples persisted in various other forms, by the middle of the sixteenth century most slaves in the Spanish Americas originated in Upper Guinea, typically arriving via the Cape Verde Islands. These enslaved women, men, and children were joined by others from Lower Guinea and West Central Africa who were first collected in São Tomé, then transported to the Americas.

The first slave trade voyage known to have sailed directly from Africa to the Americas arrived in Santo Domingo, on the island Española (Hispaniola), in 1525. The ship’s cargo consisted of nearly 200 captives purchased in São Tomé. Several additional slave ships disembarked enslaved Africans in Española, Cuba, Puerto Rico, and Jamaica during the late 1520s and 1530s. Taxes paid by slave merchants in Spain suggest that an average of about 1,200 African captives were transported to the Americas each year from the mid-1540s to 1580, though the actual numbers may have been considerably higher. While some enslaved Africans were sent to labor in mines, and in some cases sugar plantations, others were employed in traditional occupations performed by slaves in Iberia, such as street vending, domestic service, artisanal labor, construction, maritime labor, agriculture, and animal husbandry.

Beginning in the 1560s, Spain’s legendary Indies fleets departed yearly for the Americas following a fixed trajectory; a few galleons regularly stopped in the Cape Verde Islands, and possibly São Tomé, to purchase captives en route to Americas. When “the fleet” arrived in Veracruz, enslaved Africans were disembarked along with merchandise destined for Mexico City or elsewhere in the viceroyalty of New Spain (colonial Mexico). The same applied to “the galleons” arriving at the Cartagena de Indias / Nombre de Dios / Portobelo port complex known as “Tierra Firme.” From the isthmus of Panama, many African captives were subsequently transported to the viceroyalty of Peru. By the 1590s, Lima’s black population numbered from 4,000 to 7,000. During the mid-seventeenth century, travelers visiting the viceroyalties of Peru and New Spain estimated that each contained up to 60,000 black inhabitants, if not more.

The earliest known direct slave trade voyages to Brazil disembarked captives in Pernambuco in 1574 and 1575. Brazil’s indigenous populations were not decimated to the same degree as those of the Caribbean, and the outright capture and enslavement of Brazil’s native populations continued well into the eighteenth century. Despite this continued reliance on forced native labor, enslaved Africans played increasingly important social and economic roles in colonial Brazil, beginning in the second half of the sixteenth century. Black slaves were commonly employed in sugar cultivation, as well as in other forms of agriculture and urban occupations. By the century’s end, Indian slaves outnumbered Africans in some of Brazilian captaincies, but this situation was reversed in others. Bahia’s population during the mid-1580s included only 3,000 to 4,000 Africans; meanwhile, various sources suggest that during the same period, anywhere from 5,000 to 15,000 black slaves lived in the captaincy of Pernambuco.

The union of the Spanish and Portuguese crowns during the years 1580 to 1640 signaled the rise of a new era in the transatlantic slave trade. While the change may have been less noticeable in Brazilian ports such as Pernambuco, Salvador da Bahia, and Rio de Janeiro, after 1580 the Spanish Americas were directly connected to Portuguese-controlled slaving hubs in Atlantic Africa for the first time, resulting in unprecedented growth in the scale and volume of slave traffic to Spain’s American colonies. Another factor contributing to an increase in the slave trade’s volume during the late sixteenth and early seventeenth centuries was the rise of Luanda, capital of the Portuguese colony of Angola. Within just a few decades of its founding in 1575, Luanda and its hinterlands became increasingly important within the overall slave trade, exporting thousands upon thousands of West Central Africans to the Americas.

The years from 1595 to 1640 are perhaps best known as the period of the “Portuguese asientos.” Several powerful Portuguese men, including at one point the governor of Angola, signed a series of asientos or contracts with the Spanish Crown stipulating that certain numbers of Africans would be supplied to the Americas during certain years. For example, Pedro Gomez Reinel agreed to be responsible for arranging the transportation of 4,250 enslaved Africans to the Spanish Americas every year for a period of six years, beginning in 1595.

Estimates of the total volume of the transatlantic slave trade during this forty-five-year-period range from 200,000 to 300,000 enslaved Africans landed in the Spanish Americas. The differences in estimates proposed thus far may largely be explained by uncertainties regarding the frequency of contraband slave trading that, by all accounts, was endemic and widespread. In order to evade customs taxes, slave ship crews frequently concealed captives, or disembarked extra captives in secondary ports. Other voyages were completely unregistered; we know of their existence only because Spanish American officials apprehended some slave ships’ crew members, who typically claimed to have been “blown off course” while bound for some other destination, or “pursued by enemies” and “forced to land.”

From 1595 to 1640, the transatlantic slave trade to the Spanish Americas was largely concentrated in just three American ports: Cartagena de Indias, Veracruz, and Buenos Aires. This concentration increased in 1604, when in an effort to limit contraband, the Crown decreed that transatlantic slave ships were authorized to disembark captives in either Cartagena or Veracruz, but nowhere else (though some exceptions were also made for Buenos Aires several years later). Port entry records for the Spanish Americas’ most important slaving hub provide a glimpse of the slave trade’s intensity at the beginning of this period: during the nine years from 1593 to 1601, nearly 150 slave ships arrived in Cartagena alone, disembarking approximately 26,000 enslaved Africans in the city’s port.

Though historians have only recently begun to pay serious attention to the large-scale interactions between Iberia, Atlantic Africa, and the Americas between 1440 and 1640, it is clear that the slaving networks established during this era constituted, in the words of Antonio de Almeida Mendes, “the foundations of the system.” To some extent, the massive transatlantic slave trades of the eighteenth and nineteenth centuries may be portrayed quite simply as new iterations, or adaptations, of earlier Iberian models. Even the history of Africans’ forced migration to English-speaking North America, from the disembarkation of small numbers of captives in Virginia during the early 1600s, to the arrival of the slave ship Clotilda in Mobile in 1860, may be seen as one more extension of an older, deeper process rooted in the Iberian Atlantic world.


David Wheat, an assistant professor of Latin American and Caribbean History at Michigan State University, is working on a book project entitled Atlantic Africa & the Spanish Caribbean, 1570–1640.

Make Gilder Lehrman your Home for History


Already have an account?

Please click here to login and access this page.

How to subscribe

Click here to get a free subscription if you are a K-12 educator or student, and here for more information on the Affiliate School Program, which provides even more benefits.

Otherwise, click here for information on a paid subscription for those who are not K-12 educators or students.

Make Gilder Lehrman your Home for History


Become an Affiliate School to have free access to the Gilder Lehrman site and all its features.

Click here to start your Affiliate School application today! You will have free access while your application is being processed.

Individual K-12 educators and students can also get a free subscription to the site by making a site account with a school-affiliated email address. Click here to do so now!

Make Gilder Lehrman your Home for History


Why Gilder Lehrman?

Your subscription grants you access to archives of rare historical documents, lectures by top historians, and a wealth of original historical material, while also helping to support history education in schools nationwide. Click here to see the kinds of historical resources to which you'll have access and here to read more about the Institute's educational programs.

Individual subscription: $25

Click here to sign up for an individual subscription to the Gilder Lehrman site.

Make Gilder Lehrman your Home for History


Upgrade your Account

We're sorry, but it looks as though you do not have access to the full Gilder Lehrman site.

All K-12 educators receive free subscriptions to the Gilder Lehrman site, and our Affiliate School members gain even more benefits!

How to Subscribe

K-12 educator or student? Click here to edit your profile and indicate this, giving you free access, and here for more information on the Affiliate School Program.

Not a educator or student? Click here for more information on purchasing a subscription to the Gilder Lehrman site.

Add comment

Login or register to post comments