reserving the right to deviate, on occasion, from thefixed cycle. Thus the kings
did not entirely relinquish control of the calendar; however, their priority was
now to establish a standard calendar for the whole empire.
The evolution of the Babylonian calendar in the Achaemenid and later
periods—with the regularization of the beginning of the month, and even
more distinctively, thefixing of intercalation—was thus not led by scientific
discoveries, but by political objectives. These objectives were not peculiar to
the Achaemenid dynasty, but also shared by the Seleucids and common,
indeed, to all the great empires that established themselves thereafter in the
Near East.^136 In the course of subsequent centuries, the rise of vast empires
together with the need, perceived or real, for a single official calendar within
them was to lead to the increasingfixation of calendars that had previously
beenflexible. The use offixed, homogeneous calendars across the empires
became, in administrative as well as in cultural terms, an important source of
cohesion in the ancient world.
(^136) Similar motives led the Achaemenids, as we shall see in Ch. 4, to institute a new Persian
calendar that was used in the northern and eastern sectors of the Empire, which was non-lunar
and completelyfixed.
The Babylonian Calendar 123