Al-Andalus and the long frontier
Muslim armies crossed from North Africa in 711 and took most of Iberia within a decade; the peninsula they ruled — al-Andalus — became, under the Umayyad emirs and caliphs of Córdoba, one of medieval Europe’s wealthiest and most learned societies, its capital boasting libraries, street lighting, and a tolerated (if subordinate) Christian and Jewish life that produced figures from the philosopher Averroes to Maimonides. Christian remnant kingdoms in the northern mountains — the traditional starting gun is the skirmish of Covadonga, c. 722, inflated by later chroniclers into providence — spent centuries expanding, feuding, and intermarrying southward.
“Reconquista” is the retrospective banner over that eight-century mess, and historians handle it with tongs: the frontier ran on raid, tribute, and alliance as much as crusade — the Cid, national hero, fought for Muslim paymasters too; Christian kings collected parias protection money from Muslim taifa states; and in Toledo after 1085, translation schools staffed by Jews, Christians, and Muslims poured Arabic-preserved Greek science — and Arabic numerals — into Latin Europe.
The tide
The turning tide had dates nonetheless. The Córdoban caliphate’s collapse (1031) fragmented al-Andalus into taifa kingdoms that bought or begged protection; two Berber fundamentalist empires (Almoravids, Almohads) reunified and hardened it; and at Las Navas de Tolosa in 1212 a papal-blessed coalition of the Christian kingdoms broke Almohad power. Córdoba fell in 1236, Seville in 1248 — leaving, for its last quarter-millennium, the tributary emirate of Granada behind its mountains, building the Alhambra while paying for time.
1492
The union of Ferdinand of Aragon and Isabella of Castile ended the arrangement; after a decade’s war, Granada surrendered on 2 January 1492. The year became a hinge of world history in three acts: the conquest’s completion; the Alhambra Decree expelling Spain’s Jews (the Sephardic diaspora dates from it); and, financed on the victory’s momentum, Columbus’s first voyage — conquest’s energies and personnel rolling directly onto the Atlantic. The surrender terms’ religious guarantees died within a decade: forced conversions bred the Inquisition’s suspect classes of conversos and moriscos, until the Moriscos’ final expulsion in 1609 emptied Spain of the last heirs of al-Andalus. The Reconquista’s afterlife as national myth — Santiago Matamoros, Franco’s crusade rhetoric, modern political sloganeering — has proven as durable as its history, and considerably simpler.