The transition into the Early Middle Ages was a gradual and localised process. Rural areas rose as power centres whilst urban areas declined. Although a greater number of Christians remained in the East (Greek areas), important developments were underway in the West (Latin areas), and each took on distinctive shapes. The bishops of Rome, the popes, were forced to adapt to drastically changing circumstances. Maintaining only nominal allegiance to the emperor, they were forced to negotiate balances with the "barbarian rulers" of the former Roman provinces. In the East, the Church maintained its structure and character and evolved more slowly.

In Christianity's ancient Pentarchy, five patriarchies held special eminence: the sees of Rome, Constantinople, Jerusalem, Antioch, and Alexandria. The prestige of most of these sees depended in part on their apostolic founders, or in the case of Byzantium/Constantinople, that it was the new seat of the continuing Eastern Roman, or Byzantine Empire. These bishops considered themselves the successors of those apostles. In addition, all five cities were early centres of Christianity, they lost their importance after the Levant was conquered by the Sunni Caliphate.