Old Persian calendar Old Persian inscriptions and tablets indicate that early Iranians used a 360-day calendar based on the solar observation directly and modified for their beliefs. Days were not named. The months had two or three divisions depending on the phase of the moon. Twelve months of 30 days were named for festivals or activities of the pastoral year. An intercalation month was added periodically to keep the calendar synchronized with the seasons.
Old Persian calendar Old Persian inscriptions and tablets indicate that early Iranians used a 360-day calendar based on the solar observation directly and modified for their beliefs Days were not named. The months had two or three divisions depending on the phase of the moon. Twelve months of 30 days were named for festivals or activities of the pastoral year. An intercalation month was added periodically to keep the calendar synchronized with the seasons.