For the apostles Peter and especially Paul Rome was the capital of the Gentile world, and therefore became a focus of Gentile Christianity. The identification of interest between Church and Empire left the legacy that Christianity is commonly thought of as a European religion, even in an age when the majority of believers are not Europeans, and the conversion of Constantine the Great and of his successors other than Julian reinforced a conviction already widely held among the Christians of the Mediterranean world.
But the missionary spirit of the ancient churches looked beyond the frontier. To this day there are substantial Christian bodies with ancient roots in countries where Christianity is not necessarily the predominant allegiance of most of the inhabitants. The Armenians, centred on their much contested native land, were soon rooted in the Holy Land with an ecclesial body at Jerusalem, and the natural abilities of the race carried them to form a colony in Constantinople. The Armenians acquired an extensive dispersion. Unlike the Greek churches of Orthodox tradition they used unleavened bread for the Eucharist, a fact which caused some sharp differentiation in medieval times. They dissented from the Christological Definition of the Council of Chalcedon to which it is unclear whether they were actually invited. In any event Persian hostilities at the time were giving them grave matters to think about. The libraries of the Armenian Church have preserved ancient Christian documents otherwise lost, notably an early version of Irenaeus and the attack on the council of Chalcedon by Timothy the Weasel (Ailouros). The detachment of the Armenians from doctrine and customs normative in the Greek Orthodox communities no doubt assisted the survival of their churches under Persian pressure.
In Persia most of the Christians were expatriates from the Roman Empire, which did not help to assimilate them with the indigenous people. The Persian churches had their focus not at Antioch in Syria but at Seleucia- Ctesiphon (Koke); this structure of authority was in fact set up at the suggestion of the patriarchate of Antioch which sent a deputy, bishop Marutha of Maipherqat, to urge this ordered organization on them at their synod in 410. Fourteen years later their synod formally declared independence of the west. It was also important that they and the Romans (i.e. of New Rome)