linguistic:paraphrasing
New World voyages and Treaty of Tordesillas

Seven months before the treaty of Alcaçovas, King John II of Aragon died, and his son Ferdinand II of Aragon, married to Isabella I of Castile, inherited the thrones of the Crown of Aragon. The two became known as the Catholic Monarchs, with their marriage a personal union that created a relationship between the Crown of Aragon and Castile, each with their own administrations, but ruled jointly by the two monarchs.

Ferdinand and Isabella defeated the last Muslim king out of Granada in 1492 after a ten-year war. The Catholic Monarchs then negotiated with Christopher Columbus, a Genoese sailor attempting to reach Cipangu (Japan) by sailing west. Castile was already engaged in a race of exploration with Portugal to reach the Far East by sea when Columbus made his bold proposal to Isabella. In the Capitulations of Santa Fe, dated on 17 April 1492, Christopher Columbus obtained from the Catholic Monarchs his appointment as viceroy and governor in the lands already discovered and that he might discover thenceforth; thereby, it was the first document to establish an administrative organization in the Indies. Columbus' discoveries began the Spanish colonization of the Americas. Spain's claim to these lands was solidified by the Inter caetera papal bull dated 4 May 1493, and Dudum siquidem on 26 September 1493.

Since the Portuguese wanted to keep the line of demarcation of Alcaçovas running east and west along a latitude south of Cape Bojador, a compromise was worked out and incorporated in the Treaty of Tordesillas, dated on 7 June 1494, in which the world was split into two dividing Spanish and Portuguese claims. These actions gave Spain exclusive rights to establish colonies in all of the New World from north to south (later with the exception of Brazil, which Portuguese commander Pedro Álvares Cabral encountered in 1500), as well as the easternmost parts of Asia. The Treaty of Tordesillas was confirmed by Pope Julius II in the bull Ea quae pro bono pacis on 24 January 1506.

The Treaty of Tordesillas and the treaty of Cintra (18 September 1509) established the limits of the Kingdom of Fez for Portugal, and the Castilian expansion was allowed outside these limits, beginning with the conquest of Melilla in 1497.