The title "King of Portugal" refers to the monarch who ruled over the Kingdom of Portugal, which existed from 1139 until the establishment of the Portuguese Republic in 1910. The monarchy played a significant role in Portugal's history, overseeing periods of exploration, expansion, and cultural development. Notable kings include Afonso I, the first king, and John I, who established the Aviz dynasty. The last king was Manuel II, who reigned from 1908 until the monarchy was abolished. The end of the monarchy marked a significant shift in Portugal's political landscape, leading to the establishment of a republican government and the eventual rise of Salazar's Estado Novo regime in the 20th century.