The period of the Caliphate is seen by Muslim writers as the golden age of al-Andalus. Crops produced using irrigation, along with food imported from the Middle East, provided the area around Córdoba and some other Andalusī cities with an agricultural economic sector by far the most advanced in Europe. Among European cities, Córdoba under the Caliphate, with a population of perhaps 500,000, eventually overtook Constantinople as the largest and most prosperous city in Europe.[16] Within the Islamic world, Córdoba was one of the leading cultural centres. The work of its most important philosophers and scientists (notably Abulcasis and Averroes) had a major influence on the intellectual life of medieval Europe.
Muslims and non-Muslims often came from abroad to study in the famous libraries and universities of al-Andalus after the reconquista of Toledo in 1085 . The most noted of these was Michael Scot (c. 1175 to c. 1235), who took the works of Ibn Rushd ("Averroes") and Ibn Sina ("Avicenna") to Italy. This transmission was to have a significant impact on the formation of the European Renaissance.
The society of Al-Andalus was made up of three main religious groups: Christians, Muslims and Jews. The Muslims, though united on the religious level, had several ethnic divisions, the main being the distinction between the Berbers and the Arabs. Mozarabs were Christians that had long lived under Muslim rule and so had adopted many Arabic customs, art and words, while still maintaining their Christian rituals and their own Romance languages. Each of these communities inhabited distinct neighborhoods in the cities. In the 10th century a massive conversion of Christians took place, so that muladies (Muslims of ethnic Iberian origin) comprised the majority of the population of Al-Andalus by the century's end.[18]
The Berbers, who made up the bulk of the invaders, lived in the mountainous regions of what is now the north of Portugal and in the Meseta Central, while the Arabs settled in the south and in the Ebro Valley in the northeast. The Jews worked mainly as tax collectors, in trade, or as doctors or ambassadors. At the end of the fifteenth century there were about 50,000 Jews in Granada and roughly 100,000 in the whole of Islamic Iberia.[19]