Zompist Bboard Again

It should also be noted that by that time the Portuguese had already gone down the coastline of Africa and was setting up colonies along the way.

And, the map Pabappa posted shows itself that first, the Pope drew a line, and then, the Spanish and Portuguese governments moved that line.

A summary of what happened with Brazil:
Portugal was granted years before Columbus rights over all non-Christian lands south of the Canary Islands, first by treaty with Spain and later confirmed by papal bull.
After Columbus, Spain got a Spanish-born pope (one of Borgias) to make a new papal bull giving everything west of 100 leagues from the Azores and Canary Islands to Spain. The Portugese were not happy, and negotiated with Spain to move the line in the Treaty of Tordesillas. The antimeridian was used in the Treaty of Zaragoza to define the eastern limits between the empires. In practice, both sides violated the treaty - Portugal expanded far beyond the allowed limits of Brazil, and the Philippines were in the Portuguese sphere. Both sides agreed to not press on it.