The relationship of the the Egyptians and Nubians became peaceful with cultural interchange, religion and mixed marriages. Nubians and Egyptians were often so closely related that some scholars consider them virtually indistinguishable, as the two cultures melded and mixed together. Christianity entered the region by the 4th century. In 719 the church of Nubia transferred its allegiance from the Greek (Christian) Orthodox Church to the Coptic Orthodox Church. In the 7th century the influx of Arab traders introduced Islam to Nubia and it gradually supplanted Christianity. In the 14th century the region became dominated by Egypt which at that time was Islamic.