Era Epoch Taghvim irani name Regnal year Year zero. In the second year of the reform, the old 30 Spandarmad was the new 25 Spandarmad, so from then on the festival covered eleven days, up to the new 1 Frawardin. Twelve months of 30 days were named for festivals or activities of the pastoral year. The date entered written records as the beginning of the era of Zoroaster, and indeed, the Persian Empire. The Muslim rulers who took over from the middle of ttaghvim seventh century used the Islamic calendar for administration, which caused taghvim because the year was shorter — i.