the identity of the old Iranian calendar is to be inferred through parallelism, a
parallel with the Old Persian calendar—which we know was lunar—would be
just as plausible. Moreover, in ancient India itself the dominant calendar is
known, again through Vedic sources, to have been lunar, whereas the 360-day
sāvanayear seems only to have functioned in certain contexts as a simplified
scheme.^76 Thus even if the Indo-Iranian parallel is preferred, it should lead to
the conclusion that the original Iranian calendar was most likely lunar.^77
Furthermore, if the adoption of the Egyptian calendar consisted only of
improving a pre-existing, Iranian 360-day calendar by addingfive epagomenal
days, it would not have been necessary to make the months of this new
calendar conterminous with the Egyptian months: much easier would have
been to preserve without change the months in the year of the calendar
reform. The adoption of the Egyptian calendar whole piece, with contermi-
nous months, suggests a radical break from previous calendrical practice.
This radical innovation, even if instigated (as I have argued above) by
Achaemenid rulers rather than by Zoroastrian priests, seems atfirst sight
unwarranted in the context of the calendars in existence in this period. If
the Achaemenids were only seeking to institute an official, imperial calendar, a
lunar calendar would have been perfectly adequate.We know that the Old
Persian calendar was lunar—and so also, as we have just seen, other Iranian
calendars—and largely adaptable to the Babylonian calendar. If most peoples
in the Achaemenid Empire used a lunar calendar, a good option would have
been to merge Babylonian and Persian/Iranian lunar calendars—much in the
same way as the Seleucids were later to achieve with their Babylonian Mace-
donian calendar.
The choice of the Egyptian calendar, however, may have been dictated by
the administrative advantages of afixed calendar that could be reckoned
identically, without local variation, across the wide territorial expanses of the
Empire.^78 As we have seen in Chapter 2, the Babylonian calendar which was
used as the official imperial calendar was based on new moon sightings and, in
(^76) Similar to the Babylonian ideal 360-day year (on which see Ch. 2, near nn. 55–7); see de
Blois (2006) 47, and more generally, Shamasashtry (1912) and Chakravarty (1975). 77
Accounts of the length of the moon’s phases inYašt7,Yasna1. 8, 2. 8, including the
designation of specific days (in groups offive) within the moon’s cycle as auspicious or
inauspicious, are taken by de Blois (2006: 45–9) as evidence that the early Avestan calendar
was lunar. These passages certainly suggest that the days of the moon’s cycle were carefully
reckoned, even if the existence of a fully constituted lunar calendar (that may have been used for
civil or other religious purposes) is not explicitly attested, and even if there is no evidence of any
practice of intercalation.
(^78) A similar suggestion is made by Boyce (1975–91) ii. 243–5 (see also ead. 2005: 7), although
she attributes the institution of this calendar to Zoroastrian priests. It seems to me that
uniformity of calendrical practice would have been less a concern to Zoroastrian priests than
to those in charge of administrating the empire. On whether any importance was attached, in
ancient religions, to the simultaneous observance of festivals in different places, see further Ch. 7.
TheRise of the Fixed Calendars 189