>>545250
This is how the Pentarchy came to be:
Rome was founded by Peter and Paul, the greatest of the apostles, and because Rome was the capital of the Roman Empire, it became a large and well-known Church very quick. Thus it was recognized very early on to have a primacy over all other Churches, and people would often write directly to the Bishop of Rome for advice and such, due to them being the direct successor to the two greatest apostles, and thus having a very solid apostolic tradition, while it wasn't necessarily as clear in some other Churches.
Alexandria was founded by Mark, who was sent by Peter, and was also a large and well-known Church.
Antioch was again founded by Peter and Paul, and was a large and well-known Church.
In the 4th century, Byzantium became the new capital of the Roman Empire and was renamed Constantinople. As a result, a lot of the geopolitical focus that used to be on Rome moved there, and the Church of Constantinople, the New Rome, wanted to be recognized as a Patriarchate too. The First Council of Constantinople had in its canons that Constantinople would be second in honor and primacy next to Rome, which was accepted canonically, but caused controversy and notably rejection from Rome. The problem here was of course that Constantinople wanted overnight to have primacy over Alexandria and Antioch.
Nonetheless, it tried again to be recognized as being second in honor to Rome, and after a while this became accepted in the East (although Rome wouldn't accept Constantinople's position as second in honor to Rome until the 13th century, when it would make its own Latin Patriarchate of Constantinople after the schism).
Jerusalem was also recognized from early on as having a certain place of honor, due to being literally the first and most ancient Church, but its small size prevented it from having a recognized primacy as a Patriarchate. Nonetheless, it would end up being recognized as one of the 5 ancient Patriarchates too.
So there you have it: Rome, Constantinople, Alexandria, Antioch, Jerusalem. But it was not some kind of clear doctrine that all agreed on - indeed, it was mainly an ecclesiastical thing, and views in Rome and in Constantinople (and in Alexandria) varied a lot. It just wasn't seen as reason enough to have a schism.
>>545189
Let me add some notes
>He felt that he should have higher authority than the other Patriarchs to have a central head of Church
>Obviously other Patriarchs didn't like this
The division between East and West on the Papacy actually happened really late. It might be more accurate to say that the Pope was recognized as the head of the Church, and as having primacy over the whole Church, but the relation between Rome and the other Churches would be unclear, as it sometimes acted like a "big sister" Church and sometimes like a "Mother" Church.
>West uses unleavened communion bread because it was the type used at last supper.
>East uses Leavened bread because Christ raises things up.
It's recognized that, according to John, Christ used leavened bread, and according to the synoptics, Christ used unleavened bread. The tradition in the East always used leavened bread and so it was recognized that while the last supper did take place during the feast of unleavened bread in the synoptics, Christ ate leavened bread there (the Greek certainly doesn't try to make a difference) and so did it illegally.
But the whole controversy over leavened vs unleavened bread was basically nonsense, or rather, nitpicking at the Armenian "heretics" and then extending this nitpicking to the Latin "heretics".
cont