Well it was mostly controlled by Muslim Emirates at around 711AD until the Four Iberian powers, Castille, Aragon Galicia (They didnt last very long and were absorbed by Leon and Castille) and Leon initiated the Reconquista, which was the reclaiming of the Iberian Peninsula for the Iberians. This lasted for over 700 years and ended in 1492 with the fall of Islamic Granada in 1492. During this time there was The Iberian Wedding which occurred in 1462 which united Castille and Aragon. During this time Portugal also broke away from Leon and became an independent Kingdom in 1139. Leon was weakened by this and eventually joined Castille in 1230. Castille was powerful but it was never able to take over Portugal by force and Portugal was a strong colonist and trade power. Castille and Portugal were united in 1580 due to a Portugese succession crisis. This created the Iberian Union joining all three Iberian crowns of Castille, Aragon and Portugal into one Union. However this Union ended in 1640 after the Portugese revolted due to a decision on taxes that affected the Portugese very heavily. This ended the Iberian Union and after that the Portugese soon found themselves allied with the British and 300 years or so later here we are.