What was the Treaty of Tordesillas, and how did it divide overseas claims between Spain and Portugal?

The Treaty of Tordesillas, signed on June 7, 1494, was an agreement between Spain and Portugal to resolve conflicts over lands explored by Christopher Columbus and other voyagers.1

It established a line of demarcation from pole to pole, originally set by Pope Alexander VI at 100 leagues west of the Cape Verde Islands. Dissatisfied with this, Portugal negotiated to move the line to 370 leagues west of the islands.12

Under this division:
* Spain was granted exclusive rights to newly discovered lands west of the line.1
* Portugal was granted rights to lands east of the line, which secured its control over Africa, the sea route to India, and eventually the coast of Brazil.13

While intended to divide the world into spheres of influence, the treaty was never accepted by other European powers and was later supplemented by the Treaty of Saragossa in 1529 to address claims in the Pacific.12