About the middle of the eighth century Constantine, surnamed Copronymus, either as a favor or as a punishment, transplanted a great number of Paulicians into Thrace, an outpost of the empire; and there they acted as a religious mission. By this emigration their doctrines were introduced and diffused in Europe. They seem to have labored with great success amongst the Bulgarians. It was in order to guard the infant church of Bulgaria, that Peter of Sicily, about the year 870, addressed to the archbishop of the Bulgarians a tract warning him against the infection of the Paulicians. This document is the chief source of information as to the sect. In the tenth century the Emperor John Zimisces conducted another great migration to the valleys of Mount Haemus. Their history after this period is European. They were favored with a free toleration in the land of their exile, which greatly softened their condition and strenghened their community. From these Bulgarian settlements their way was opened into Western Europe. Many native Bulgarians associated with them; hence the name of Bulgarians, in a course or corrupted form, is one of the appellations of hatred, which clung to the Paulicians in all quarters.
As to the subsequent religious history of these interesting people historians are greatly divided. Nothing is known of them but from the writings of their enemies; therefore, in common justice, we are bound to suspend our belief of their statements. One thing however is certain: they protested against the saint and image-worship of the catholics, and the legitimacy of the priesthood by which idolatry was upheld. They also protested against many things in the doctrines, the discipline, and the assumed authority of the church of Rome. The catholic writers usually speak of them as Manicheans -the most odious of all heretics. But there are some protestant writers, who have examined with great care all that can throw light on their history, and have come to the conclusion, that they were guiltless of the heresies imputed to them, and maintain that they were the true and faithful witnesses of Christ and His truth during a very dark period of the middle ages.
We now turn to our general history.