time, large Moorish populations became established, especially in the Guadalquivir River valley, the coastal plain of Valencia, the Ebro River valley and (towards the end of this period) in the mountainous region of Granada. A series of Viking incursions raided the coasts of the Iberian Peninsula in the 9th and 10th centuries. The first recorded Viking raid on Iberia took place in 844; it ended in failure with many Vikings killed by the Galicians' ballistas; and seventy of the Vikings' longships captured on the beach and burned by the troops of King Ramiro I of Asturias. Córdoba, the capital of the caliphate since Abd-ar-Rahman III, was the largest, richest and most sophisticated city in western Europe. Mediterranean trade and cultural exchange flourished. Muslims imported a rich intellectual tradition from the Middle East and North Africa. Some important philosophers at the time were Averroes, Ibn Arabi and Maimonides. The Romanised cultures of the Iberian Peninsula interacted with Muslim and Jewish cultures in complex ways, giving the region a distinctive culture. Outside the cities, where the vast majority lived, the land ownership system from Roman times remained largely intact as Muslim leaders rarely dispossessed landowners and the introduction of new crops and techniques led to an expansion of agriculture introducing new produces which originally came from Asia or the former territories of the Roman Empire. In the 11th century, the Caliphate of Córdoba collapsed, fracturing into a series of petty kingdoms (Taifas), often subject to the payment of a form of protection money (Parias) to the Northern Christian kingdoms, which otherwise undertook a southward territorial expansion. The capture of the strategic city of Toledo in 1085 marked a significant shift in the balance of power in favour of the Christian kingdoms. The arrival from North Africa of the Islamic ruling sects of the Almoravids and the Almohads achieved temporary unity upon the Muslim-ruled territory, with a stricter, less tolerant application of Islam, and partially reversed some Christian territorial gains. The Kingdom of León was the strongest Christian kingdom for centuries. In 1188 the first modern parliamentary session in Europe was held in León (Cortes of León). The Kingdom of Castile, formed from Leonese territory, was its successor as strongest kingdom. The kings and the nobility fought for power and influence in this period. The example of the Roman emperors influenced the political objective of the Crown, while the nobles benefited from feudalism.