The collection of largely forged decretals by Pseudo-Isidore was probably composed in the Frankish monastery of Corbie during the second quarter of the ninth century. The material was presented in a way that made the fraud difficult to detect. Thus, forged decretal letters ascribed to the earliest bishops of Rome were believed to be authentic throughout the Middle Ages. The chief purpose of the forgery seems to have been to free the church from secular (i.e., imperial) influence by strengthening the authority and independence of bishops, and to affirm the inviolability of the see of Rome. The collection circulated widely. It was cited in political and theological conflicts, and it would be an important source of canon law. The chapter also describes other forgeries in the same family of texts, collectively referred to as the Pseudo-Isidorian forgeries.