Important manuscripts were found in Apt concerning music in the 12th/13th centuries. They are known as the Apt Manuscript and the Ivrea Codex. They contain motets and mass movements, all of which are polyphonic. Nine out of fourteen Motets by Philippe de Vitry are recorded in the Ivrea Codex, a compilation of eighty-one compositions dating to 1360. It is purported to have been derived from the repertoire used in the Papal Palace at Avignon, since it is so close and offers a sampling of music from the Ars Nova movement.