The Codex of Guardiagrele contained several pieces composed by artists from the Abruzzo and from other regions which worked in Guardiagrele at the church of Santa Maria Maggiore. These compositions clearly show that the musical production of polyphonic works was rich in this region. The Codex is composed by several compositions of the early 1400 kept into mauscript of liturgic missals conserved until 1979 in Guardiagrele (in the province of Chieti). They are a gradual and an anthiphonary of three and four volumes respectively and a psalter, all written on a parchment arranged in folio of great dimensions.