On June 7, 1494, the Treaty of Tordesillas established the division of exploration zones in the Atlantic Ocean between the Crown of Castile and Portugal.
This pact avoided a conflict between both powers and had direct consequences on European expansion toward America, Africa, and Asia.
The signing took place in the town of Tordesillas, in the province of Valladolid, a Castilian enclave that thus became the scene of one of the most important diplomatic decisions of the late 15th century.
Castile and Portugal as maritime powers
At the end of the 15th century, Castile and Portugal were the two main maritime powers of the Iberian Peninsula.
While Portugal had spent decades exploring the African coast in search of a trade route to Asia, Castile had just financed the voyage of Christopher Columbus, who arrived in American lands in 1492.
The discovery sparked an immediate dispute. Both kingdoms wanted to secure control of the new oceanic routes and the territories that might be found in the Atlantic.
At that time, navigation was also a source of wealth, as it allowed access to new markets, precious metals, and trade routes hitherto unknown to Europe.
The causes that led to the agreement
The rivalry between Castile and Portugal
Before 1492, Portugal had an advantage in maritime exploration. It had advanced along the coast of Africa and controlled important trade routes.
Columbus's arrival changed that situation, as Castile claimed the new lands discovered to the west. That change altered the balance between both crowns and increased diplomatic tension within a few months.
The Pope's mediation
To avoid a war, Alexander VI intervened. The pontiff issued bulls that granted Castile rights over the new lands, but Portugal rejected those limits and demanded a renegotiation.
That tension led to the negotiations in Tordesillas.
How the world was divided between Castile and Portugal
The line of demarcation
The treaty set an imaginary line located 370 leagues west of the Cape Verde Islands. Everything discovered to the east would belong to Portugal; everything located to the west would belong to Castile.
Although it may seem like a simple division today, at that time cartography was limited and there were no precise maps of the lands being discovered, so establishing an exact boundary was much more complex than it currently seems.
What did it mean in practice?
The agreement did not only divide seas. It also determined who could claim territories, establish colonies, exploit resources, and control trade routes.
It was a partition of the known world and of future lands that might be discovered.
The consequences of the Treaty of Tordesillas
Castilian expansion in America
Thanks to the treaty, Castile secured the majority of America.
This allowed for the consolidation of Castilian expansion in the Atlantic and laid the foundations for the future Spanish presence in a large part of the American continent, and consolidated the Castilian presence on the continent.
From then on, Castilian expeditions increased and the conquest of new territories on the American continent accelerated.
Portugal, trade routes, and Brazil
Portugal maintained control of its maritime and trade routes to Africa and Asia.
In addition, part of the coast of Brazil fell within its zone, which favored its subsequent Portuguese colonization.
Change in world geopolitics
The treaty influenced global history. The division agreed upon in 1494 explains why Brazil speaks Portuguese and most of Latin America speaks Castilian.
It also turned the Iberian Peninsula into the center of European maritime expansion.
The historical importance of the agreement
The Treaty of Tordesillas was one of the most influential diplomatic agreements of the Modern Age.
It regulated Atlantic exploration, avoided a war between Castile and Portugal, and marked the beginning of a new stage in the history of Spain, Portugal, and America.
Its influence was so lasting that it is still considered today to be one of the key documents for understanding the colonial division of the world among European powers.
