Whereas in the East the Church maintained its structure and character and evolved more slowly, in the West the Bishops of Rome (the popes) were forced to adapt more quickly and flexibly to drastically changing circumstances. In particular, whereas the bishops of the East maintained clear allegiance to the Eastern Roman emperor, the Bishop of Rome, while maintaining nominal allegiance to the Eastern emperor, was forced to negotiate delicate balances with the "barbarian rulers" of the former Western provinces. Although the greater number of Christians remained in the East, the developments in the West would set the stage for major developments in the Christian world during the later Middle Ages.