Dudum siquidem

Dudum siquidem (Latin for "A short while ago") was a papal bull issued by Pope Alexander VI on 26 September 1493, one of the Bulls of Donation addressed to the Catholic Monarchs Isabella I of Castile and Ferdinand II of Aragon which supplemented the bull Inter caetera and purported to grant to them "all islands and mainlands whatsoever, found and to be found, discovered and to be discovered, that are or may be or may seem to be in the route of navigation or travel towards the west or south, whether they be in western parts, or in the regions of the south and east and of India".

The bull Aeterni regis of 1481, delivered by Pope Sixtus IV, had confirmed the substance of the Treaty of Alcáçovas, which itself had confirmed Castile in its possession of the Canary Islands and had granted to Portugal all further new lands to be won by Christendom in Africa and the East Indies.

At the beginning of the year 1492 the Christian reconquest of Spain was completed by the capture of Granada. The voyages of Christopher Columbus, seeking a westerly route to the riches of the Indies, began in the summer of the same year, and on 12 October Columbus sighted land in the West Indies which he believed to be part of India. He returned to Spain, with news of what he had found, in March 1493. Columbus's discoveries in the annus mirabilis created a competitive frenzy between the two principal sea-powers of the day, Portugal, and the new Spanish kingdom based on Castile and Aragon.

...
Wikipedia