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.
Turkey
In 324, Constantine I chose Byzantium to be the new capital of the Roman Empire, renaming it New Rome. Following the death of Theodosius I in 395 and the permanent division of the Roman Empire between his two sons, the city, which would popularly come to be known as Constantinople, became the capital of the Eastern Roman Empire. This empire, which would later be branded by historians as the Byzantine Empire, ruled most of the territory of present-day Turkey until the Late Middle Ages; although the eastern regions remained in firm Sasanian hands up to the first half of the seventh century. The frequent Byzantine-Sassanid Wars, as part of the centuries long-lasting Roman-Persian Wars, fought between the neighbouring rivalling Byzantines and Sasanians, took place in various parts of present-day Turkey and decided much of the latter's history from the fourth century up to the first half of the seventh century.