Christianity in Turkey
Constantinople became established in the ecclesiastical hierarchy at the Council of Constantinople in 381. Second only to Rome, the legendary origins of the Patriarchate of Constantinople go back to St. Andrew, Metrophanes and Alexander of Constantinople. Constantinople's primacy over the Patriarchates of Alexandria and Antioch was reaffirmed at the Council of Chalcedon in 481, after which the papacy in Rome supported Constantinople in its dispute with Alexandria over monophysitism. Later, when Rome sought to assert its primacy over Byzantium, the Eastern Orthodox church developed the doctrine of pentarchy as a response.
Byzantine Empire under the Constantinian and Valentinian dynasties
Byzantium under the Constantinian and Valentinian dynasties was the earliest period of the Byzantine history that saw a shift in government from Rome in the west to Constantinople in the East within the Roman Empire under emperor Constantine the Great and his successors. Constantinople, formally named Nova Roma, was created on the site of the old Greek Byzantium, which is the origin of the historiographical name for the Eastern Empire, which self-identified simply as the "Roman Empire".