The ground work for his successes had certainly been laid by others: Michael III, who broke the power of Melitene at Lalakaon; Basil I, who destroyed the Paulicians; Leo VI the Wise, who founded the vital theme of Mesopotamia; and Empress Zoe, who extended Byzantine influence again into Armenia and founded the theme of Lykandos.
While Petar's reign witnessed the spread of the Bogomil heresy, its origins were more demographic (perhaps inspired by Paulicians settled earlier by Byzantine emperors in Thrace) than social, and the Bulgarian Orthodox Church canonized him as a saint.