Torben S. Hansen :
'Reconquista og convivencia - Muslims, Jews, and Christians in medieval Spain'

In terms of economy, urbanization and intellectual achievements al-Andalus, the Arab civilisation in the Iberian Peninsula, represented by far the highest level in medieval Europe, and Western Christianity received basic knowledge of medicine, astronomy and philosophy from Muslim and Jewish scholars in Seville and Toledo. However, perennial vendettas between quarrelling clans and a refractory aristocracy sapped the strength of the Muslim princes who were unable to build a strong polity as a precondition for crushing the Christian principalities in the Northern areas of the peninsula and eventually repulse their continuous reconquista - "reconquest" - of the territories of al Andalus. Thus in the middle of the 13th century the Muslims suffered crushing military defeats and lost huge areas with fertile land and populous cities, and Islam as a faith and a culture was doomed in 1492 when "the Catholic Kings" - Isabel of Castile and Fernando of Aragon - conquered the last "moorish" kingdom of Granada.