The Zoroastrian sacred text is the Avesta ("Book of the Law"), a fragmentary collection of sacred writings. Compiled over many centuries, the Avesta was not completed until Persia's Sassanid dynasty (226-641 CE).
It consists of: liturgical works with hymns ascribed to Zarathustra (the Gathas); invocations and rituals to be used at festivals; hymns of praise; and spells against demons and prescriptions for purification.