Petrus Siculus
Petrus Siculus or Peter Sikeliotes () was either a monk or a learned nobleman, who in 870 was sent as a legate from the Byzantine emperor Basil I to the Paulician leader Chrysocheir, negotiating for an exchange of prisoners. He stayed in the Paulician city of Tephrike/Tibrica, now Divrigi in Turkey, on the upper Euphrates, for nine months. While there he wrote his "Historia Manichaeorum qui Pauliciani dicuntur", which is one of the main sources for the history of the Paulician sect. The "Historia Manichaeorum" was first published by Rader in Ingolstadt in 1604.