The origin of the Pentarchy (Five Patriarchates)

The earliest churches, founded by the Apostles, were governed by a plurality of elders, as confirmed by church father Jerome in the 4th century.

By the end of the first century the leading elder, who would preside at the church gathering, preach and celebrated the Lord's Supper, came to be known as bishop. It was he who was responsible for receiving, preserving and passing on the Apostolic Teaching.

In a further development the bishop in the capital city of a given province, which was often also the mother church (first founded), came to be known as the metropolitan and had certain rights over the other bishops in his province, who were known as suffragan bishops.

By the third century, the metropolitans in capitals of dioceses (provinces were grouped into dioceses) came to be known as exarchs, mirroring the political structure of the Roman Empire. For example in the diocese of Thrace, the bishop of Heraclea was an exarch, in Asia Ephesus and in Pontus Caesarea.

In 325 at the First Ecumenical Council at Nicaea, after the accession of Constantine, it was ruled as follows: "Let the ancient customs in Egypt, Libya and Pentapolis prevail, that the Bishop of Alexandria have jurisdiction in all these, since the like is customary for the Bishop of Rome also. Likewise in Antioch and the other provinces, let the Churches retain their privileges." (Canon 6)

At the Second Ecumenical Council in 381 it was added, "Because it is new Rome, the bishop of Constantinople is to enjoy the privileges of honour after the bishop of Rome." (Canon 3) The Fourth Ecumenical Council later clarified the jurisdiction of Constantinople, "Consequently, the metropolitans and they alone of the dioceses of Pontus, Asia and Thrace, as well as the bishops among the barbarians of the aforementioned dioceses, are to be ordained by the previously mentioned very holy see of the very holy Church of Constantinople; that is, each metropolitan of the above-mentioned dioceses is to ordain the bishops of the province along with the fellow bishops of that province as has been provided for in the divine canons." (Canon 28) In other words those metropolitans with their see in diocesan capitals (exarchs) of Caesarea, Ephesus and Heraclea were now subject to the higher, ordaining authority of Constantinople.

We can see this pyramid-like structure (bishop-metropolitan-exarch-Constantinople) in canon IX of the Fourth Ecumenical Council: "If any Clergyman has a dispute with another, let him not leave his own Bishop and resort to secular courts, but let him first submit his case to his own Bishop, or let it be tried by referees chosen by both parties and approved by the Bishop. Let anyone who acts contrary hereto be liable to Canonical penalties. If, on the other hand, a Clergyman has a dispute with his own Bishop, or with some other Bishop, let it be tried by the Synod of the province. But if any Bishop or Clergyman has a dispute with the Metropolitan of the same province, let him apply either to the Exarch of the diocese or to the throne of the imperial capital Constantinople, and let it be tried before him."

At the same Council of 451 Jerusalem was granted autonomy from the See of Antioch and "the bishop of Jerusalem, or rather the most holy Church which is under him, shall have under his own power the three Palestines".

These five elevated episcopal sees, Rome, Constantinople, Alexandria, Antioch and Jerusalem, which enjoyed "jurisdiction" and "privileges of honour", were later designated 'patriarchates' by Justinian in 531.

Within the Empire Cyprus had autocephalous (autonomous) status from 431.

Outwith the Empire, the heads of churches were designated Catholicoi (singular 'Catholicos'), e.g. the Sassinian Church or the Armenian Church.