Against this backdrop of depressingly widespread corruption and cynicism, a religious movement known as the pataria arose in the Archdiocese of Milan, aimed at reforming the clergy and ecclesiastic government in the province.

It was influenced by the southern French church reform movements Catharism and the Peace and Truth of God—perhaps as the result of one of its founders, Arialdo of Carimate, having been educated at Laon and Paris.

Members of the pataria were called patarini.