The Iberian Union was a dynastic union that lasted from 1580 to 1640, uniting the kingdoms of Portugal and Spain under a single monarch. This occurred when the Portuguese King Sebastian I died without an heir, leading to a succession crisis. The Spanish King Philip II claimed the Portuguese throne, and the two kingdoms were ruled together, although they maintained separate laws and administrations. During the Iberian Union, both kingdoms faced challenges, including conflicts with other European powers and colonial rivals. The union ended in 1640 when Portugal restored its independence, leading to the establishment of the House of Braganza as the new ruling dynasty in Portugal.