intercalate may have been largely a matter of royal decree, as implicit in the
following letter from Hammurabi (king of Babylon in 1848– 1806 BCE):
Tell Sin-iddinam, Hammurabi sends you the following message:‘This year has an
additional month. The coming month should be designated as the second month
of Ululu, and wherever the annual tax has been ordered to be brought in to
Babylon on the 24th of the month of Tashritu, it should now be brought to
Babylon on the 24th of the second month of Ululu’(Labat 1939: 26; Britton and
Walker 1996: 45).The months that could be repeated (and thus intercalary) varied widely from
one city to the next. Even within one calendar (e.g. at Mari) several months of
the year could be made intercalary, although the intercalation of the last
month of the year (month XII) was already then preponderant.^80 Thefluidity
of intercalation in this early period might explain why festivals of the same
name occur in different months of the year in different cities.^81
The standard Babylonian calendar, which emerged towards the end of the
second millennium, appears to have been considerably more regular: its
intercalations were made at fairly regular intervals, and were restricted to
months VI and XII (i.e. second Ululu or second Addaru) only. In the neo-
Assyrian period (eighth–seventh centuriesBCE), significant evidence begins to
emerge about how these intercalations were made. But continuous lists of
intercalated years can only be compiled from the neo-Babylonian to the early
Seleucid periods (late seventh–early second centuriesBCE).
Intercalation in the neo-Assyrian and neo-Babylonian periodsSources from the neo-Assyrian and neo-Babylonian periods indicate that the
intercalation of a 13th month, similarly to the determination of the beginning
of the month, depended on both scholarly expertise and royal authority.
Scholarly expertise is dominant in the following letters from the Assyrian
astrologer Balasî, in which he appears to be making all the decisions:
As regards the adding of the intercalary month which the king wrote to me, this is
indeed an intercalated year. After Jupiter has become visible, I shall write again to
the king, my lord. I am waiting for it; it will take the whole month. Then we shall
see how it is and when we have to add the intercalary month.^82(^80) Greengus (1987) 212, 214 n. 20, 220–1; (2001) 262.
(^81) See Greengus (2001) 259.
(^82) Parpola (1970–83) i, no. 38 (partially cited in Brown 2000: 196), dated late in Nisannu 670
BCE(Parpola 1970–83: ii. 45; but see Brown 2000: 270).
The Babylonian Calendar 95