The compilation of the Avesta can be authoritatively traced, however, to the Sasanian Empire, of which only fraction survive today if the Middle Persian literature is correct. The later manuscripts all date from after the fall of the Sasanian Empire, the latest being from 1288, 590 years after the fall of the Sasanian Empire. The texts that remain today are the Gathas, Yasna, Visperad and the Vendidad, of which the latter's inclusion is disputed within the faith. Along with these texts is the individual, communal, and ceremonial prayer book called the Khordeh Avesta, which contains the Yashts and other important hymns, prayers, and rituals. The rest of the materials from the Avesta are called "Avestan fragments" in that they are written in Avestan, incomplete, and generally of unknown provenance.