Liutprand of Cremona, but he apparently posed no threat to Peter's authority. Perhaps taking advantage of these challenges to Peter's rule, the Prince of Serbia Časlav Klonimirović escaped the Bulgarian capital Preslav in 933 and, with tacit Byzantine support, managed to raise a Serbian revolt against Bulgarian rule. The revolt succeeded and Serbia recovered its independence. Peter may have had to also face the incursions of the Magyars, who had been defeated and forced into Pannonia by his father in 896. Perhaps after an initial defeat, Peter came to terms with the enemy and now used Magyar groups as his allies against Serbia. Various Magyar clans and chieftains appear to have begun to settle in what was still Bulgarian territory north of the Danube, where they may have become Bulgarian federates, enjoying independence from the Árpád dynasty. This arrangement paved the way for the eventual loss of the region to the Magyars, although that happened over the half-century following Peter's death. Peter apparently allowed these groups to cross Bulgaria and raid Byzantine territories in Thrace and Macedonia, perhaps as an underhanded reaction against Byzantine support for the Serbian rebellion. Domestic rule Peter I presided over a long and relatively peaceful reign, albeit one poorly illuminated by foreign or native sources. In spite of the challenges he encountered soon after his accession and the critical situation at the very end of his life, Peter's Bulgaria appears to have been prosperous and increasingly well organized, with an administrative apparatus noted by foreign travelers and confirmed by the numerous finds of imperial seals. Peter was particularly generous towards the Church, which he endowed lavishly throughout his reign. The emperor's generosity reached such an extent that it was seen as a corrupting factor by even Orthodox clerics, like Cosmas Presbyter. Others chose a path away from the temptations of the secular world, most notably Saint Ivan of Rila, but their ascetic existence still drew the attention of the monarch. Luxury and social tensions may have contributed to the spread of the Bogomil heresy, which Peter duly undertook to combat, soliciting the advice of famous hermits and even his uncle-in-law, Patriarch Theophylact of Constantinople. Conflict with Byzantium and Rus Relations with the Byzantine Empire worsened after the death of Peter's wife in the mid-960s. Victorious over the Arabs, Emperor Nikephoros II Phokas refused to pay the annual tribute to Bulgaria in 966, complaining of the