Pagan religion did not depend on a very elaborate institutional structure, and the cults of each city were all organized locally; rabbinic Judaism, too, was very decentralized (Jews did have a single patriarch until around 425, but it is unclear how wide his powers were). Christianity, however, had a complex hierarchy, partly matching that of the state. By 400 there were four patriarchs, at Rome, Constantinople (since 381), Antioch and Alexandria (a fifth, Jerusalem, was added in 451), who oversaw the bishops of each city... Bishops were soon arrayed in two levels, with metropolitan bishops (called in later centuries archbishops) at an intermediate level, overseeing and consecrating the bishops of each secular province. Inside the dioceses of each bishop, which normally covered the secular territory of their city, bishops had authority over the clerics of other public churches... The church in the fourth and fifth centuries became an elaborate structure, with perhaps a hundred thousand clerics of different types, more than the civil administration, and steadily increasing in wealth as a result of pious gifts. It was not part of the state, but its wealth and empire-wide institutional cohesion made it an inevitable partner for emperors and prefects, and a strong and influential informal authority in cities; the cathedral church by 500 was often the largest local landowner (and therefore patron), and, unlike in the case of private family wealth, its stability could be guaranteed – bishops were not allowed to alienate church property... Even in a church context, bishops generally identified themselves with their diocese first, with wider ecclesiastical institutions only secondarily. But they were linked to the wider church hierarchy all the same: they could be called to order and dismissed by metropolitans and by the councils of bishops that steadily became more frequent, whether empire-wide (the ‘ecumenical’ councils) or at the regional level, in Spain or Gaul or Africa. The fact that this institutional structure did not depend on the empire, and was above all separately funded, meant that it could survive the political fragmentation of the fifth century, and the church was indeed the Roman institution that continued with least change into the early Middle Ages; the links between regions became weaker, but the rest remained intact.