Two crowns drew a line and claimed half the planet
On 7 June 1494 at Tordesillas, Portugal and Castile split non-European lands along a meridian about 370 leagues west of Cape Verde. The pope later blessed the bargain; Indigenous nations never agreed—and Protestant powers simply ignored the map.
Columbus's 1493 return triggered the crisis. Portugal's John II cited the 1479 Treaty of Alcácovas and the 1481 bull Aeterni regis to claim everything south of the Canaries. Pope Alexander VI's Inter caetera of 4 May 1493 drew a pole-to-pole line only 100 leagues west of the Azores or Cape Verde, favoring Castile; Dudum siquidem in September even gestured at India. John negotiated the line 270 leagues farther west so Portugal kept its African route and later rights to eastern Brazil—a move one scholar called a Portuguese diplomatic triumph.
Spain ratified on 2 July 1494, Portugal on 5 September, and Pope Julius II on 24 January 1506. East of the line went to Portugal, west to Castile. Pedro Álvares Cabral's 1500 Brazilian landfall fell on Portugal's side; some historians argue the coast was already known. The 1529 Treaty of Zaragoza set the antimeridian for the other hemisphere. Spain and Portugal mostly respected the deals until the 1750 Treaty of Madrid, even during the 1580–1640 Iberian Union, while England, the Dutch Republic, and France refused to recognize a papal two-power world.
The treaty never defined the league, the reference island, or Earth's circumference, and the promised joint survey voyage never sailed. Experts disagreed for decades: Jaime Ferrer in 1495 put a line near 42°25′W on an oversized globe; the Cantino planisphere of 1501–02 implies about 42°30′W; Badajoz conferees in 1524 nearly matched Portuguese and Spanish figures near 47°W yet settled nothing. UNESCO added Tordesillas to its Memory of the World register in 2007; originals sit in Seville's Archive of the Indies and Lisbon's Torre do Tombo.
Source: Treaty of Tordesillas
