Treaty of Alcáçovas (1479): The World’s First Colonial Partition Treaty

Map created by reddit user FairyCelebiThe map above shows the theorical division of the world in the Treaty of Alcáçovas in 1479.

From the author:

The Treaty of Alcáçovas was signed on 4 September, 1479, between the Catholic Monarchs of Castile and Aragon and Portugal.

It put an end to the War of the Castilian Succession.

In addition to various dynastic agreements regarding the future of the Castilian and Portuguese thrones, several territorial recognitions took place:

• Castile obtained recognition of the Canary Islands.
• Portugal obtained recognition of Madeira, the Azores, Cape Verde, and Guinea.
• Furthermore, Portugal was granted the right to conquer and explore ALL lands below a few hundred kilometers below the Canary Islands. This concession also included the Kingdom of Fez, now part of Morocco.
• The rest of the world, north of the Portuguese line of exclusivity, remained “open” to all, not just Castile.

(Note that at the time, it was unclear how much land there was, and that America and Oceania had not yet been reached by Europeans)

Portugal was also tasked by the Pope to colonize and evangelize the lands assigned to them.

The treaty quickly fell into disuse and was definitively replaced in 1494 by the Treaty of Tordésillias.

Here’s a clear comparison and context for each, focusing on their role in partitioning global influence:

Treaty of Alcáçovas (1479)

Parties:

• Castile (Spain) – represented by the Catholic Monarchs Ferdinand and Isabella
• Portugal – represented by King Afonso V and Prince John (future John II)

Context:

• This treaty ended the War of the Castilian Succession (1475-1479), fought partly over who should inherit Castile’s throne.
• Beyond the succession issue, it also settled rival claims in the Atlantic, where both Portugal and Castile were expanding.

Key Provisions (World Division):

• Portugal recognized Isabella and Ferdinand as rulers of Castile.
• Castile recognized Portugal’s exclusive rights over:
  • The Madeira, Azores, and Cape Verde Islands
  • The Gulf of Guinea coast (thus control of the West African gold trade and early slave trade routes)
  • Any discoveries south of the Canary Islands
• Castile kept the Canary Islands, giving them their only Atlantic stepping stone toward future westward expansion.

Significance:

• This was the first formal division of the Atlantic world between two European powers.
• It gave Portugal a monopoly over the route around Africa to India and most of the known Atlantic islands, while leaving Spain with fewer options – which helped motivate Columbus’s westward voyage.

Treaty of Tordesillas (1494)

Parties:

• Spain (Castile and Aragon)
• Portugal

Context:

• After Columbus’s 1492 voyage, Spain claimed the “New World,” alarming Portugal.
• Pope Alexander VI initially issued bulls (papal decrees) in 1493 granting Spain control of lands west of a meridian 100 leagues west of the Azores/Cape Verde. Portugal negotiated to move the line further west to secure more future discoveries.

Key Provisions (World Division):

• Drew an imaginary meridian line about 370 leagues west of the Cape Verde Islands (roughly 46°30′ W longitude).
• Lands east of the line belonged to Portugal.
• Lands west of the line belonged to Spain.
• No other European power was considered — this was a bilateral Iberian carve-up of the non-European world.

Significance:

• Gave Portugal claim to what would become Brazil (since its eastern bulge crossed the line).
• Cemented Spain’s dominance over most of the Americas.
• Portugal retained control over its African and Asian routes.
• This became one of the most famous examples of Eurocentric “world partitioning.”

Comparison: Alcáçovas vs. Tordesillas

Aspect	Treaty of Alcáçovas (1479)	Treaty of Tordesillas (1494)
Purpose	Ended Castilian succession war, settled Atlantic disputes	Resolved Spain–Portugal rivalry over Columbus’s discoveries
Geographic Focus	Atlantic islands & African coast	Global division by meridian (Atlantic & eventually Pacific)
Division Principle	Island-by-island & regional monopoly (Africa vs. Canaries)	Straight longitudinal line dividing all future discoveries
Outcome	Portugal gains Africa/Atlantic, Castile keeps Canaries	Spain gains most of the Americas, Portugal keeps Africa & gets Brazil
Global Impact	Precursor to worldwide European “spheres of influence”	First true global territorial division between European powers