07/17/2017 (Mon) 22:55:05
You know, how Justinian I formalised the system of pentarchy, of five supreme episcopal sees of Christianity?
Constantinople, Rome, Alexandria, Jerusalem and Antioch.
Constantinople has remained fully Orthodox.
Rome has politically split off in 8th century, and formally broke ties in 1054, spawning the Roman Catholic Church.
Alexandria has been internally divided since the Council of Chalcedon in 451, spawning the Coptic Orthodox Church.
Jerusalem hasn't had any internal splits, however the Roman Catholic Church has established its own Patriarch of Jerusalem in 1099 already, defunct in 1291, and reestablished in 1847.
Antioch as well has been divided by Chalcedonian Schism in 451, spawning (not immediately) the Syriac Orthodox Church.
Besides, there have been other subsequent schisms.
Currently, the Orthodox Church maintains Patriarchate in four of the five pentarchic episcopal sees: Constantinople (Bartholomew I), Alexandria (Theodore II), Jerusalem (Theophile III), and Antioch (John X). Only Rome is missing, and has never had an Orthodox claimant since the East-West Schism.