The largely Aramaic-speaking population of Syria during the heyday of the Byzantine Empire was probably not exceeded again until the 19th century. Prior to the ''Arab Islamic Conquest'' in the 7th century AD, the bulk of the population were Arameans, but Syria was also home to Greek and Roman ruling classes, Assyrians still dwelt in the north east, Phoenicians along the coasts, and Jewish and Armenian communities were also extant in major cities, with Nabateans and ''pre-Islamic'' Arabs such as the Lakhmids and Ghassanids dwelling in the deserts of southern Syria. Syriac Christianity had taken hold as the major religion, although others still followed Judaism, Mithraism, Manicheanism, Greco-Roman Religion, Canaanite Religion and Mesopotamian Religion. Syria's large and prosperous population made Syria one of the most important of the Roman and Byzantine provinces, particularly during the 2nd and 3rd centuries (AD).