In the middle of the ninth century there appeared in Gaul the collection of 'false decretals' commonly known as the Pseudo-Isidorian Decretals. The exact date and the circumstances of the composition of the collection are still an open question, but it is certain that Hincmar was one of the first to know of their existence, and apparently he was not aware that the documents were forged. The importance assigned by these decretals to the bishops and the provincial councils, as well as to the direct intervention of the Holy See, tended to curtail the rights of the metropolitans.