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Ancient Calendars 2: Mesopotamia

Continuing our survey of ancient calendar systems, we next turn to Mesopotamia. Unlike Egypt, Mesopotamia was rarely politically unified. Rather, for much of the region’s history each city-state functioned independently and consequently maintained its own calendar. Even so, all Mesopotamian calendars bear a strong resemblance to one another, at least superficially.

Mesopotamian calendars were lunisolar, with twelve months of 29 or 30 days and an intercalary thirteenth month added (originally in a haphazard fashion by official decree) to bring the lunar and solar years into alignment. Days are counted from sunset to sunset.

In most regions and most eras, the New Year began at the first visible lunar crescent after the vernal equinox (~22 Mar). Thus, compared to the Gregorian calendar the year begins in March or April and ends in April or May. The Babylonians grouped the days of the month into seven-day intervals, perhaps inspired by the four phases of the moon, each lasting approximately seven days. Assyrians observed either a five- or a ten-day “week” (ḫamištum).

Month names varied from city to city and from era to era. Below is a sampling of a few of the Mesopotamian calendars that can be reconstructed with some degree of confidence.

A. Early Bronze Age (Sumerian)

(Ur III)
(Ur III)
Apr Bára-zag-gar Maš-dù-kú Gán-maš
May Ezen-gu4-si-su Šeš-da-kú Gu4-du-bí-sar-sar
Jun Sig4-giš-u5-šub-ba-gar U5-bi-kú Ezen-dLi9-si4
Jul Šu-numun Ki-síg-dNin-a-zu Šu-numun
Aug NE-NE-gar Ezen-dNin-a-zu Munux(DIM4)-kú
Sep Kin-dInanna Á-ki-ti Ezen-dDumu-zi
Oct Du4-kù Ezen-dŠul-gi Ezen-dŠul-gi
Nov Giš-apin-du5-a Šu-eš-ša Ezen-dBa-ba6
Dec Gan-gan-è Ezen-maḫ Mu-šu-du7
Jan Kù-šim Ezen-an-na Amar-a-a-si
Feb Ziz-a Ezen-me-ki-gál Še-gur10-ku5
Mar Še-gur10-ku5 Še-gur10-ku5 Še-íl-la

B. Middle and Late Bronze Age (Semitic)

The Babylonians adopted the Sumerian calendar of Nippur and gave the months indigenous Akkadian names. From 380 BC onwards the Babylonians followed a predictable rule for intercalations, adding a second Elūlu in the 17th year of every 19-year cycle and adding a second Addaru in years 1, 3, 6, 9, 12, and 14. (Nisan occurs earliest in the 17th year of the cycle.) This system seems to have been in development as early as the fifth century BC, and there are fairly complete records of intercalations from about 623 BC.

Babylon Eshnunna Old Assyrian (MBA) Middle Assyrian (LBA)
Apr Nisannu Elūnum Ṣip’um Ṣippu
May Ayaru Magrattum Qarrātum Qarrātu
Jun Simānu Abum Kanwarta TANmarte
Jul Du’ūzu, Tammūzu Zibnum Te’inātum, Suen Sîn
Aug Abu Niqmum Kuzallu Kuzallu
Sep Ulūlu, Elūlu Kinūnum Allanātum Allanātu
Oct Tašrītu Tamḫīrum Bēlat ekallim Bēlat ekalli
Nov Araḫsamna Nabrium Ša sarrātim Ša sarrāte
Dec Kislīmu Mamītum Ša kēnātim Ša kēnāte
Jan Ṭebētu Nigallum Maḫḫur ilī Muḫur ilāni
Feb Šabātu Kinkum Ab šarrāni Abu šarrāni
Mar Addaru Kiskissum Ḫubur Ḫibur

Years were counted in various ways depending on the era and region. The early Babylonians used a “year name” referring to a significant event that happened during that year: a military victory, the dedication of a new temple, etc. Obviously, these names could only be assigned after the fact. Until a suitable year name was determined, reference would be made to “the year after the year such-and-such happened.”

During Kassite rule of Babylon (1531 BC, low chronology), this system was abandoned in favor of a regnal-year dating system. Years were numbered according to the regnal years of the current king. After the death of one king, the remainder of that year was counted as the accession year of his successor. The beginning of the next year marked the beginning of the new king’s first regnal year. This system, referred to as “accession reckoning” or “postdating,” continued for the remainder of Babylonian history.

The Assyrians also used a form of “year-name” system. Rather than naming the year for a significant event, however, they named it for an important royal official honored to be the eponym or limmu for that year. (For much of Assyrian history, the king himself was limmu early in his reign.) Court officers, merchants, and others could keep a list of these limmus in their proper sequence in order to establish past dates. The Assyrian limmu-lists provide for a secure Mesopotamian chronology back to 911 BC.

In the Old Assyrian period the year began in the fall (~Oct). There is no evidence for intercalation in Assyrian texts, but since limmus assumed office during the same season each year, some sort of arrangement must have existed to align the lunar and solar years (Hunger, 299; see Lewy, 44; Depuydt, 33–34). According to Lewy,

To be sure, intercalary months are mentioned neither in the Old nor in the Middle Assyrian texts. However, there is evidence that at the time of the eponym change a month was sometimes doubled in such a way that the month which ended one eponym year was repeated as the first month of the next eponym year. (44)

Furthermore, the Assyrians apparently kept a commercial calendar that diverged from the civil/religious calendar. The commercial calendar appears to have been comprised of 360 days, with an intercalary month added every sixth year (Lewy, 44). Since such a calendar would still drift with the seasons, Shalmaneser I (13th cent.) enacted a calendar adjustment to bring the seasons (temporarily) back into alignment. The Assyrians eventually adopted the Babylonian calendar around 1000 BC.


  • E. J. Bickerman, Chronology of the Ancient World, 2nd ed. (Cornell University Press, 1968).
  • ________, “calendar.” Encyclopædia Britannica. 2010. Encyclopædia Britannica Online.
  • Leo Depuydt, Civil Calendar and Lunar Calendar in Ancient Egypt (Peeters, 1997).
  • I. E. S. Edwards, C. J. Gadd, and N. G. L. Hammond, The Cambridge Ancient History: Early History of the Middle East (Cambridge University Press, 1971).
  • Hermann Hunger, “Kalender,” Reallexikon der Assyriologie und Vorderasiatischen Archäologie, ed. Erich Ebeling and Bruno Meissner (Walter de Gruyter, 1980) 299–303.
  • Hildegard Lewy, Assyria: c. 2600–1816 b.c., The Cambridge Ancient History, rev. ed. (Cambridge University Press, 1966).
  • Holger Oertel, “Several Calendars.”
  • Broughton Richmond, Time Measurement and Calendar Construction (Brill, 1956).
  • Klaas R. Veenhof and Jesper Eidem, Mesopotamia: The Old Assyrian Period (Fribourg, 2008).
  • Nick Wyatt, Space and Time in the Religious Life of the Near East (Sheffield, 2001).


  1. Nice survey. As you say, the calendars of Mesopotamia are quite complicated and vary widely depending upon period and place. An online resource that is quite helpful is the month name chart for the Ur III period at CDLI: http://cdli.ucla.edu/tools/ur3months/month.html they also have year names which is handy: http://cdli.ucla.edu/wiki/doku.php/rulers_of_mesopotamia


  2. Darrell Pursiful says:

    Thanks, Charles, and thanks for the links!


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