Treaty of Tordesillas

Agreed at the Castilian town of Tordesillas on 7 June 1494, this treaty split the lands newly found or still to be found outside Europe between Portugal and the Crown of Castile. It drew a north–south line 370 leagues west of the Cape Verde islands: territory to the east would go to Portugal, territory to the west to Castile. Made without asking the many peoples who lived in those lands, the agreement shaped the colonial map of the Americas for more than two centuries.

The quarrel began in 1493, when Christopher Columbus returned from his first Atlantic voyage, sponsored by Castile, and stopped in Lisbon on the way home (see Voyages of Christopher Columbus). King John II of Portugal claimed the new islands for himself under the Treaty of Alcáçovas of 1479 and a papal bull of 1481, which gave Portugal lands south of the Canary Islands. He threatened to send a fleet. Isabella I of Castile and Ferdinand II of Aragon insisted the islands were theirs and proposed negotiations.

In May 1493 Pope Alexander VI, born in the Spanish kingdom of Aragon, issued the bull Inter caetera, assigning to Castile all lands west of a line 100 leagues beyond the Azores or Cape Verde Islands, except lands already under Christian rule. A later bull that September went further, granting Castile lands belonging to "India" even east of the line. John II objected, because Portuguese sailors had already rounded the southern tip of Africa and India was his goal.

Rather than return to the pope, John negotiated directly with Ferdinand and Isabella. The result kept the papal division as its starting point but moved the line 270 leagues further west, to 370 leagues from the Cape Verde islands, roughly halfway between them and Columbus's discoveries. Castile ratified the treaty on 2 July 1494 and Portugal on 5 September. Pope Julius II confirmed it in 1506. Because the treaty did not define the league or say which island the distance was measured from, the line's exact position was never agreed, and experts later placed it at various points between about 42 and 50 degrees west.

The new line protected Portugal's route around Africa and, as it turned out, gave it the eastern bulge of South America. In 1500 Pedro Álvares Cabral reached the coast of what became Brazil while sailing to India; some historians argue the Portuguese already suspected the land was there. Almost everything else in the Americas fell on the Castilian side, the basis of the later Spanish Empire. Spain did not resist Portuguese settlers who later pushed Brazil's frontier well west of the line.

Once Portugal reached the spice-producing Moluccas in 1512, and survivors of Magellan's expedition arrived there in 1521, Spain argued that the line ran right round the globe and put the islands on its side. The Treaty of Zaragoza of 22 April 1529 settled the matter: Spain gave up its claim in return for 350,000 ducats, and a second line was set 17 degrees east of the Moluccas. The Philippines lay on the Portuguese side, yet Spain colonised them from 1565 onwards.

Other European powers rejected a world divided between two Catholic kingdoms. King Francis I of France reportedly asked to see the clause in Adam's will that excluded him from his share. Even when Spain and Portugal shared a king from 1580 to 1640, the division stayed in place, until the Treaty of Madrid of 1750 declared it void and drew new borders in South America. UNESCO added the treaty to its Memory of the World register in 2007.

Our 1492 map shows Castile and Portugal on the eve of the voyages, and our 1530 map shows the first results of the division, with the Spanish Empire in the Americas and the Portuguese Empire in Brazil, Africa and Asia.