the political unity achieved by his father, accepting the Catholic faith in the Third Council of Toledo (589 CE). The religious unity established by this council was the basis of that fusion of Goths with Hispano-Romans which produced the Spanish nation. Sisebut and Suintila completed the expulsion of the Byzantines from Spain. Intermarriage between Visigoths and Hispano-Romans was prohibited, though in practice it could not be entirely prevented and was eventually legalised by Liuvigild. The Spanish-Gothic scholars such as Braulio of Zaragoza and Isidore of Seville played an important role in keeping the classical Greek and Roman culture. Isidore was one of the most influential clerics and philosophers in the Middle Ages in Europe, and his theories were also vital to the conversion of the Visigothic Kingdom from an Arian domain to a Catholic one in the Councils of Toledo. Isidore created the first western encyclopedia which had a huge impact during the Middle Ages. Muslim era and Reconquista From 711 to 718, as part of the expansion of the Umayyad Caliphate, which had conquered North Africa from the Byzantine Empire, nearly all of the Iberian Peninsula was conquered by Muslim armies from across the Strait of Gibraltar, resulting in the collapse of the Visigothic Kingdom. Only a small area in the mountainous north of the peninsula stood out of the territory seized during the initial invasion. The Kingdom of Asturias-León consolidated upon this pocket of territory. Other Christian kingdoms such as Navarre and Aragon in the mountainous north eventually surged upon the consolidation of counties of the Carolingian Marca Hispanica. For several centuries, the fluctuating frontier between the Muslim and Christian controlled areas of the peninsula was along the Ebro and Douro valleys. Under Islamic law, Christians and Jews were given the subordinate status of dhimmi. This status permitted Christians and Jews to practice their religions as People of the Book but they were required to pay a special tax and had legal and social rights inferior to those of Muslims. Conversion to Islam proceeded at an increasing pace. The muladíes (Muslims of ethnic Iberian origin) are believed to have formed the majority of the population of Al-Andalus by the end of the 10th century. The Muslim society was itself diverse and beset by social tensions. The North-African Berber peoples, who had provided the bulk of the invading armies, clashed with the Arab leadership from the Middle East. Over