The Kingdom of Portugal was a European monarchy that existed from the 12th century until the early 19th century. It emerged in 1139 when Afonso I declared himself king after a successful campaign against the Moors. The kingdom played a significant role in the Age of Discovery, establishing a vast maritime empire that included territories in Africa, Asia, and South America. Throughout its history, the Kingdom of Portugal experienced periods of prosperity and decline, influenced by factors such as exploration, trade, and dynastic unions. The kingdom officially ended in 1822 when Brazil, its largest colony, gained independence, leading to the eventual establishment of the Portuguese Republic in 1910.