The papacy (the pope, his authority and Curia Romana ) developed slowly over the centuries. In the beginning, all bishops were considered equal, with the bishop of Rome considered a little more equal because the first bishop there had been Peter (chosen by Jesus as the chief apostle). But a large number of capable bishops of Rome gradually turned the See of Peter into the supreme religious leader of the Roman Catholic church. Much credit must be given to the Moslems, who wiped out the North African Christian church (in the 7th century) and greatly diminished the number of Byzantine catholics (from the 7th to 15th centuries). These were the two major competitors for supreme authority in the church, or at least resistance to Roman supremacy. The Roman and Byzantine churches split in the 11th century over a number of issues (some doctrinal, some having to do with the power of the bishop of Rome). As early as the 8th century, the bishops of Rome had learned how to play one king against another to keep the papacy in power., both spiritually and temporally, particularly in the States of the Church . The popes supported the kings as those "divinly appointed to rule" and the kings reciprocated by looking after the church's interests. This was technique that was to continue throughout the Medieval period and into the modern period..