In the early church the first leaders were Bishops. Then arch-bishops, then Patriarchs. The title pope comes from patriarch. There were 5 of them in Rome, Constantinople, Antioch, Jerusalem, and Alexandria. These 5 were the bosses of the christian faith. There were 2 others though 1 in Armenia. And a 7th who was patriarch of the east. Basically the Sassanid empire. His seat was at Ctestiphon.