Until about the 12th century, all Zoroastrians followed the same 365-day religious calendar, which had remained largely unmodified since the calendar reforms of Ardashir I (r. 226-241 AD). Since that calendar did not compensate for the fractional days that go to make up a full solar year, with time it was no longer accordant with the seasons.
until about the 12th century all zoroastrians followed the same 365-day religious calendar which had remained largely unmodified since the calendar reforms of ardashir i (r 226-241 ad) since that calendar did not compensate for the fractional days that go to make up a full solar year with time it was no longer accordant with the seasons