Treaty of Madrid (13 January 1750)

The Spanish–Portuguese treaty of 1750 or Treaty of Madrid was a document signed in the Spanish capital by Ferdinand VI of Spain and John V of Portugal on 13 January 1750, to end armed conflict over a border dispute between the Spanish and Portuguese empires in South America in the vicinity of the Uruguay River, an area known as the Banda Oriental (now comprising parts of Uruguay, Argentina and the state of Rio Grande do Sul, Brazil). The treaty established borders between the Spanish and Portuguese empires, ceding much of what is today's country of Brazil to the Portuguese.

Earlier treaties such as the Treaty of Tordesillas and the Treaty of Zaragoza authored by both countries, and as mediated by Pope Alexander VI, stipulated that the Portuguese empire in South America could extend no farther west than 370 leagues west of Cape Verde Islands (called the Tordesillas meridian, approx. the 46th meridian). Had these treaties remained unchanged, the Spanish would have held both what is today the city of São Paulo and all land to the west and south. Thus, Brazil would be only a fraction of its present-day size.

1534
Brazil according to the Treaty of Tordesillas

Starting in the 17th century, Portuguese explorers, traders, and missionaries from the state of Maranhao in the north, and gold-seekers and slave-hunters, the famous bandeirantes of São Paulo, in the south, had penetrated far to the west and far to the south of the old imaginary treaty-line.

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