The Castilian Crown refers to the monarchy that ruled over the Kingdom of Castile, a significant medieval kingdom in what is now modern-day Spain. Established in the 11th century, it played a crucial role in the Reconquista, the effort to reclaim the Iberian Peninsula from Muslim rule. The crown was instrumental in the unification of Spain, particularly through the marriage of Isabella I of Castile and Ferdinand II of Aragon in 1469. The Castilian Crown was known for its strong central authority and the promotion of the Spanish language and culture. It also oversaw the exploration and colonization of the Americas, leading to the establishment of a vast empire. The legacy of the Castilian Crown continues to influence Spain's cultural and historical identity today.