Discovery of Brazil
Treaty of Tordesillas

In the XV century, several agreements were signed in order to avoid a military confrontation between Portugal and Spain. The Papal bull Aeterni regis of pope Sixto IV from 1481 confirmed the treaty of Alcáçovas-Toledo from 1479, granting all territories south of the Canarian islands to Portugal.

The bull Inter Coetera of pope Alexandre VI from 1493 established a division of the world by a meridian located 100 leagues west of the archipelago of Cape Verde. All land east of this imaginary demarcation line should belong to Portugal and all land west to Spain.

By the Treaty of Tordesillas (1494), Portuguese cosmographer Duarte Pacheco Pereira negotiated a relocation of this line 270 leagues further to the west. This became the juridical base for Pedro Álvares Cabral's official discovery of Brazil on April 22, 1500.

As this treaty neither specified the starting point of the 370 leagues (the archipelago extends for 2º42´ degrees of longitude) nor the length of the league (depending on navigator and country, there were used between 16 2/3 and 18 leagues per degree of longitude), the interpretations of the exact postion of the Tordesillas - line varied substantially.

Based on a division of a degree of longitude into 17,5 leagues and the starting point of the 370 leagues in the centre of the archipelago of Cape Verde (24ºW), its postition would be located at about 45,14º W (somewhere between São Paulo and Rio de Janeiro).