Treaty of Tordesillas

In 1493 Spain and Portugal, the two leading maritime powers of Europe, turned to the papacy to settle rival claims to lands newly reached by Atlantic voyages. The dispute was resolved the following year by the Treaty of Tordesillas, which divided the non-European world into two spheres of influence. The agreement shaped the languages, borders, and colonial histories of much of the Americas, Africa, and Asia.

The background was Portuguese expansion down the African coast through the fifteenth century. An earlier agreement, the Treaty of Alcáçovas of 1479, had recognized Portuguese rights to lands south of the Canary Islands, while Castile kept the Canaries. When Christopher Columbus returned in 1493 from his first voyage under the Spanish crown, King John II of Portugal argued that the lands he had found might fall within Portugal's sphere. The Spanish monarchs, Ferdinand and Isabella, appealed to Pope Alexander VI, a Spaniard by birth.

The pope issued several bulls in 1493, including Inter caetera, which drew a north-south line in the Atlantic roughly 100 leagues west of the Azores and Cape Verde Islands. Lands beyond it to the west were assigned to Spain. Portugal considered this too generous to Spain, since it threatened its route around Africa, and negotiated directly with the Spanish crown. In June 1494, the two kingdoms signed the treaty at Tordesillas in Castile, moving the line to 370 leagues west of the Cape Verde Islands. Spain gained rights to the west, and Portugal to the east. Pope Julius II later confirmed the arrangement, in 1506.

The treaty's practical meaning was uncertain from the start. Sailors could not reliably measure longitude, so the line's exact position was disputed, as was the length of a league. Its most famous consequence is usually linked to Brazil. When Portuguese ships reached the South American coast in 1500, the bulge of land lay east of the line, which gave Portugal a basis for its claim and helps explain why Portuguese is spoken there while Spanish dominates most of the continent. The line's counterpart on the opposite side of the globe was left undefined, which caused a later quarrel over the Spice Islands and was addressed by the Treaty of Zaragoza in 1529.

The treaty had limits as well. England, France, and the Dutch Republic never accepted that a pope or two kingdoms could divide the world, and they later established their own colonies in the Americas. Indigenous peoples, whose lands were being allocated, were not consulted. Even so, Tordesillas remains an early example of European powers using diplomacy and religious authority to carve up territory they barely understood.