The Reconquista (Spanish, Portuguese and Galician for "reconquest") is a historiographical construction of the approximately 781 year period in the history of the Iberian Peninsula between the Umayyad conquest of Hispania in 711 and the fall of the Nasrid kingdom of Granada in 1492, in which the Christian kingdoms expanded through war and conquered al-Andalus, or the territories of Iberia ruled by Muslims.The beginning of the Reconquista is traditionally marked with the Battle of Covadonga (718 or 722), the first known victory by Christian military forces in Hispania since the 711 military invasion which was undertaken by combined Arab-Berber forces. The rebels who were led by Pelagius defeated a Muslim army in the mountains of northern Hispania and established the independent Christian Kingdom of Asturias.In the late 10th century, the Umayyad vizier Almanzor waged military campaigns for 30 years to subjugate the northern Christian kingdoms. His armies ravaged the north, even sacking the great Santiago de Compostela Cathedral. When the government of Crdoba disintegrated in the early 11th century, a series of petty successor states known as taifas emerged. The northern kingdoms took advantage of this situation and struck deep into al-Andalus; they fostered civil war, intimidated the weakened taifas, and made them pay large tributes (parias) for "protection".

After a Muslim resurgence under the Almohads in the 12th century, the great Moorish strongholds in the south fell to Christian forces in the 13th century after the decisive battle of Las Navas de Tolosa (1212)Crdoba in 1236 and Seville in 1248leaving only the Muslim enclave of Granada as a tributary state in the south. After 1492, the entire peninsula was controlled by Christian rulers. The conquest was followed by a series of edicts (14991526) which forced the conversions of Muslims in Spain, who were later expelled from the Iberian peninsula by the decrees of King Philip III in 1609. Likewise, on 30 July 1492, all the Jewish community some 200,000 people were forcibly expelled.

Beginning in the 19th century, traditional historiography has used the term Reconquista for what was earlier thought of as a restoration of the Visigothic Kingdom over conquered territories. The concept of Reconquista, consolidated in Spanish historiography in the second half of the 19th century, was associated with the development of a Spanish national identity, emphasizing nationalistic and romantic aspects.

The Catholic Monarchs were Queen Isabella I of Castile and King Ferdinand II of Aragon, whose marriage and joint rule marked the de facto unification of Spain. They were both from the House of Trastámara and were second cousins, being both descended from John I of Castile; to remove the obstacle that this consanguinity would otherwise have posed to their marriage under canon law, they were given a papal dispensation by Sixtus IV. They married on October 19, 1469, in the city of Valladolid; Isabella was eighteen years old and Ferdinand a year younger. It is generally accepted by most scholars that the unification of Spain can essentially be traced back to the marriage of Ferdinand and Isabella.

Spain was formed as a dynastic union of two crowns rather than a unitary state, as Castile and Aragon remained separate kingdoms until the Nueva Planta decrees of 1707–1716. The court of Ferdinand and Isabella was constantly on the move, in order to bolster local support for the crown from local feudal lords. The title of "Catholic King and Queen" was officially bestowed on Ferdinand and Isabella by Pope Alexander VI in 1494, in recognition of their defence of the Catholic faith within their realms.