At some later date most scholars say many centuries after the death of Zarathustrathe remaining parts of the Avestas were written. This work was brought to completion perhaps in the fourth century, revised and finally declared canonical.
In addition to the Avesta, as above described, there are late Pahlavi works which are much used by Zoroastrians of the later periods. Persia was gradually converted to Islam after its conquest by the Arabs in the 7th century.
Introduction Zoroastrianism, religion founded in ancient Persia by the prophet Zoroaster. In ceremonial recitation the sections of the Visperad are inserted between the Yasna chapters, somewhat as the verses of the litany in church service. In Ezra 6:it is at Acmetha Ecbatana 'the palace in the province of the Medes', that the famous decree of Cyrus was found.
Both approaches are dangerous. I beseech of thee for heaventhe best life of the saints, the radiant, all-glorious. All this a separate paper on Pahlavi literature might well show.
Is there a single linear history with time coming to an end or does time recycle? Verily among all prayers It is this one which I gifted With revivifying powers.