what would later become eastern Albania took part in the First Council of Nicaea. Arianism had at that point extended to Illyria, where Arius himself had been exiled to by Constantine. Middle Ages Since the early 4th century AD, Christianity had become the established religion in the Roman Empire, supplanting pagan polytheism and eclipsing for the most part the humanistic world outlook and institutions inherited from the Greek and Roman civilizations. Ecclesiastical records during the Slavic invasions are slim. Though the country was in the fold of Byzantium, Christians in the region remained under the jurisdiction of the Roman pope until 732. In that year the iconoclast Byzantine emperor Leo III, angered by archbishops of the region because they had supported Rome in the Iconoclastic Controversy, detached the church of the province from the Roman pope and placed it under the patriarch of Constantinople. When the Christian church split in 1054 between the East and Rome, southern Albanian regions retained their ties to Constantinople while the northern areas reverted to the jurisdiction of Rome. The Albanians first appear in the historical record in Byzantine sources of the 11th century. At this point, they are already fully Christianized. Most Albanian regions belonged to the Eastern Orthodox Church after the schism, but regional Albanian populations gradually became Catholic to secure their independence from various Orthodox political entities and conversions to Catholicism would be especially notable under the aegis of the Kingdom of Albania. Flirtations with conversions to Catholicism in Central Albanian Principality of Arbanon are reported in the later 12th century, but until 1204 Central and Southern Albanians (in Epirus Nova) remained mostly Orthodox despite the growing Catholic influence in the North and were often linked to Byzantine and Bulgarian state entities Krujë, however, became an important center for the spread of Catholicism. Its bishopric had been Catholic since 1167. It was under direct dependence from the pope and it was the pope himself who consecrated the bishop. Local Albanian nobles maintained good relations with the Papacy. Its influence became so great, that it began to nominate local bishops. The Archbishopric of Durrës, one of the primary bishoprics in Albania had initially remained under the authority of Eastern Church after the split despite continuous, but fruitless efforts from the Roman church to convert it to the Latin rite. After the Fourth Crusade However, things changed after the fall of Byzantine Empire in