Without claiming to consider the complex historical question of the title of Patriarch in all its aspects, it can be stated from the historical point of view that the ancient Patriarchates of the East, set by the Councils of Constantinople (381) and of Calcedonia (451), they were related to a fairly clearly circumscribed territory, when the territory of the See of the Bishop of Rome remained vague. In the East, as part of the imperial ecclesiastical system of Justinian (527-565), alongside the four Eastern Patriarchates (Constantinople, Alexandria, Antioch and Jerusalem), the Pope was understood as the Patriarch of the West. Inversely, Rome favored the idea of the three Petrine episcopal seats: Rome, Alexandria and Antioch. Without using the title of “Patriarch of the West”, the IV Council of Constantinople (869-70), the IV Council of the Lateran (1215) and the Council of Florence (1439), listed the Pope as the first of the then five Patriarchs .