The term "Iberian Kingdom" generally refers to the historical kingdoms located on the Iberian Peninsula, primarily Spain and Portugal. These kingdoms emerged during the early Middle Ages, following the fall of the Roman Empire, and included notable entities such as the Kingdom of Castile, Kingdom of Aragon, and Kingdom of León. They played a significant role in the Reconquista, the centuries-long effort to reclaim territory from Muslim rule. The Iberian Kingdoms were characterized by a rich cultural and political history, marked by the blending of Christian, Muslim, and Jewish influences. The unification of these kingdoms in the late 15th century, particularly with the marriage of Isabella I of Castile and Ferdinand II of Aragon, laid the foundation for the modern nation of Spain.