June 7, 1494

Treaty of Tordesillas

Castilian and Portuguese envoys sign the Treaty of Tordesillas

Six diplomats — not the kings and queen — divided future Atlantic discoveries between two crowns, then sealed the bargain with their hands on the Cross and Gospels.

7 June 1494, at Tordesillas

Three representatives of Ferdinand and Isabella and three ambassadors of João II of Portugal executed and swore to a treaty at Tordesillas on 7 June 1494, settling their crowns' dispute over Atlantic discoveries.

It placed a pole-to-pole boundary 370 leagues west of the Cape Verde Islands. Discoveries east of it were assigned to Portugal, discoveries west of it to the Castilian monarchs.

What the envoys bound their sovereigns to

Beginning on the treaty date, each crown promised not to send ships into the other's zone for discovery, trade, barter or conquest, and accidental discoveries were to be surrendered to the entitled crown.

The envoys required their sovereigns to exchange ratifications within 100 days and proposed a joint voyage within ten months to determine the boundary at sea.

The text ordered pilots and astronomers from each crown to sail aboard the other crown's ships, so neither side could secretly manipulate the survey.

An undefined league and reference island

The treaty never defined the length of its league or identified which Cape Verde island the measurement started from. The planned joint demarcation voyage was never carried out.

It was a bilateral treaty rather than a papal decree, though the negotiators asked the pope to confirm it. Nor did it knowingly divide a continent — it allocated rights over islands and mainlands discovered or yet to be discovered in the "Ocean Sea."

The monarchs did not sign at Tordesillas. Ferdinand, Isabella and Prince Juan ratified on 2 July, and João II on 5 September.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes

How this was checked

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What the sources leave uncertain

“Spain” is convenient modern shorthand but imprecise for 1494. The treaty was made between the Portuguese crown and Ferdinand and Isabella’s composite monarchy; its western overseas rights were framed principally as Castilian.
The treaty did not define the length of its league or identify a particular Cape Verde island as the measurement origin. Its planned joint demarcation voyage was never carried out.