Spanish asiento contracts and the transatlantic slave trade (1503–1750)

1. Casa de Contratación founded to control Atlantic trade

   Jan 1, 1503Labels: Casa de, Seville

   In 1503, the Spanish Crown created the Casa de Contratación (House of Trade) in Seville to regulate shipping, people, and goods moving between Spain and its American colonies. This institution helped centralize imperial commerce and later became a key place for monitoring and taxing the import of enslaved Africans as “merchandise.” It set an administrative framework that later supported monopoly slave-supply contracts known as asientos.

   • Britannica
   • Casa Contrataci n

2. Genoese firm receives first asiento contract

   Jan 1, 1517Labels: Genoese firm, Asiento de

   In 1517, the Spanish Crown awarded the first widely noted asiento de negros to a Genoese company. The contractor agreed to supply a set number of enslaved Africans to Spanish America over a fixed term, in exchange for monopoly rights and payments to the Crown. This marked a shift toward outsourcing slave supply to private merchants as a regular policy tool.

   • Britannica

3. German firm granted asiento to supply 4,000 enslaved people

   Jan 1, 1528Labels: German firm, Asiento contract

   In 1528, the Crown reached an asiento agreement with a German firm to supply 4,000 enslaved Africans to Spanish America. The deal shows how Spain relied on non-Spanish merchants and financiers for access to African trading networks and shipping capacity. The asiento system also gave the Crown revenue while attempting to keep a controlled, legal supply into its colonies.

   • Britannica

4. Portuguese merchants dominate early seventeenth-century asientos

   Jan 30, 1595Labels: Portuguese merchants, Cartagena de

   From 1595 to 1640, multiple asiento contracts were granted to Portuguese merchants. These contracts concentrated legal slave imports through major Spanish-American entry ports such as Cartagena de Indias and Veracruz, where enslaved people were then distributed deeper into the Americas. The pattern reflected Portugal’s stronger access to African ports and trading networks during this period.

   • Asiento Negros

5. Asiento period of António Fernandes de Elvas begins

   Sep 27, 1615Labels: Ant nio, Asiento monopolist

   In 1615, Portuguese merchant António Fernandes de Elvas began an asiento term to supply enslaved Africans to Spanish America. His contract illustrates how single contractors could act as monopolists for years, coordinating procurement in West Africa and delivery to Spanish colonial markets. These long-running arrangements tied Spain’s colonial labor supply to private overseas trading operations.

   • Elvas
   • Asiento Negros

6. Portuguese asiento era ends with 1640 separation

   Dec 1, 1640Labels: 1640 separation, Portuguese era

   In 1640, the last of the Portuguese-held asientos listed for this period ended, aligning with the political break between Portugal and Spain. The change mattered because asiento contracts depended on international politics as much as on commerce: when alliances and dynastic control shifted, Spain often had to seek new contractors from other states or networks. This helped reshape who profited from supplying enslaved labor to Spanish colonies.

   • Asiento Negros

7. French Compagnie de Guinée holds Spanish asiento

   Jan 1, 1701Labels: Compagnie de, Jean-Baptiste du

   From 1701 to 1713, the Spanish asiento was associated with France through Jean-Baptiste du Casse and the Compagnie de Guinée. This shows the asiento becoming part of great-power rivalry, where commercial privileges could be attached to broader diplomatic and wartime goals. Control of legal access to Spanish-American markets was valuable well beyond the slave trade itself.

   • Asiento Negros

8. Treaty of Utrecht grants Britain the South Sea Company asiento

   Jan 1, 1713Labels: South Sea, Treaty of

   In 1713, the Treaty of Utrecht granted Britain an asiento that was carried out by the South Sea Company. The agreement allowed delivery of 4,800 enslaved Africans per year for 30 years and also permitted one annual “navío de permiso” (a licensed ship) to sell general trade goods in Spanish America. This combined slave supply with broader commercial access and increased tensions over smuggling and enforcement.

   • Britannica
   • South Sea

9. War of the Quadruple Alliance disrupts asiento operations

   Jan 1, 1718Labels: War of, Asiento disruptions

   The War of the Quadruple Alliance (1718–1720) was part of a wider struggle over the post-Utrecht European order and affected Spain’s overseas trade environment. Wartime conditions made the asiento harder to carry out reliably and increased conflict over seizures, inspections, and suspected illicit trade linked to the asiento system. The episode highlighted how fragile “legal” monopoly trading rights could be during war.

   • Quadruple War
   • UCL Thesis

10. War of Jenkins’ Ear begins amid asiento-related disputes

    Jan 1, 1739Labels: War of, British Spanish

    In 1739, Britain and Spain went to war in the War of Jenkins’ Ear, after years of conflict over trade rules, inspections, and alleged smuggling linked to Britain’s asiento and broader Caribbean commerce. The war disrupted the South Sea Company’s ability to deliver enslaved people and trade goods under the contract. It also shows how an economic agreement could become a direct cause of armed conflict.

    • Britannica
    • UCL Thesis

11. Treaty of Aix-la-Chapelle ends war and revives negotiations

    Oct 18, 1748Labels: Treaty of, Diplomatic revival

    In 1748, the Treaty of Aix-la-Chapelle ended the War of the Austrian Succession and helped reopen European diplomacy on unresolved commercial disputes. In the asiento context, it mattered because it created a path for Spain and Britain to revisit contested trading privileges and financial claims connected to the South Sea Company’s contract. The treaty did not solve all trade frictions, but it set the stage for a final settlement.

    • Britannica
    • Aix Treaty

12. Treaty of Madrid cancels the British asiento

    Oct 5, 1750Labels: Treaty of, British asiento

    On 5 October 1750, the Treaty of Madrid (a commercial treaty between Britain and Spain) formally ended Britain’s asiento and the navío de permiso in exchange for a £100,000 payment from Spain. This outcome marked a clear closing point for the best-known asiento arrangement and signaled Spain’s effort to reduce foreign leverage inside its colonial trade system. By this point, the asiento framework had supplied large numbers of enslaved Africans into Spanish America and had repeatedly shaped European diplomacy and conflict.

    • Madrid Treaty
    • Britannica