Zoroastrian Calendar - The Primitive, or 'Old Avestan', Calendar

The Primitive, or 'Old Avestan', Calendar

The forerunner of all modern Zoroastrian calendars is the system used to reckon dates in the Persian Empire. In 539 BCE, Persia's rulers conquered Babylon, and soon afterwards - at least by the 4th Century BCE - adopted the Babylonian method of reckoning months: 12 months each containing 30 days.

This 'Avestan Calendar' of 360 days required regular correction to keep it synchronised with the solar year; this was achieved by intercalating a 13th month roughly once every six years.

Intercalations did not always follow a regular pattern, but during the reign of Artaxerxes II (circa 380 BCE) astronomers utilised a 19 year cycle which required the edition of a month called Addaru II month in years 3, 6, 8, 11 14 and 19, and the month Ululu II in year 17 of the cycle. Older research suggests the first intercalation took place in 309 BCE. Fuller information on the naming of months will be found below, but it should be noted that the first month of the year was called Frawardin, and the first day of Frawardin was the 'New Year's Day' or Nawruz (also reckoned Now-Ruz, Nowruz, No Roz, No-Rooz, Norouz, or Navroz), from which all other religious observances were reckoned - this day being, in theory, the day of the Northern vernal equinox, 21 March (Gregorian).

Following Alexander's conquest of Persia in 330 BCE, the Seleucids (312-248 BCE) instituted the Hellenic practice of counting years from the start of an 'era', as opposed to starting a new count at the beginning of the reign of each individual king. They therefore counted years of the era of Alexander (now referred to as the Seleucid era). This practice was not considered acceptable to the Zoroastrian priests, who consequently founded a new era, the era of Zoroaster - which incidentally led to the first serious attempt to establish a historical date for the prophet. The Parthians (150-224 CE), who succeeded the Seleucids, continued the Seleucid/Hellenic tradition.