Map of Mesopotamia
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The International History Project
In Mesopotamia the solar year
was divided into two seasons, the "summer," which included the barley harvests
in the second half of May or in the beginning of June, and the "winter," which
roughly corresponded to today's fall-winter. Three seasons (Assyria) and four
seasons (Anatolia) were counted in northerly countries, but in Mesopotamia the
bipartition of the year seemed natural. As late as c. 1800 BC the prognoses for
the welfare of the city of Mari, on the middle Euphrates, were taken for six
The months began at the first
visibility of the New Moon, and in the 8th century BC court astronomers still
reported this important observation to the Assyrian kings. The names of the
months differed from city to city, and within the same Sumerian city of
Babylonia a month could have several names, derived from festivals, from tasks
(e.g., sheep shearing) usually performed in the given month, and so on,
according to local needs. On the other hand, as early as the 27th century BC,
the Sumerians had used artificial time units in referring to the tenure of some
high official--e.g., on N-day of the turn of office of PN, governor. The
Sumerian administration also needed a time unit comprising the whole
agricultural cycle; for example, from the delivery of new barley and the
settling of pertinent accounts to the next crop. This financial year began about
two months after barley cutting. For other purposes, a year began before or with
the harvest. This fluctuating and discontinuous year was not precise enough for
the meticulous accounting of Sumerian scribes, who by 2400 BC already used the
schematic year of 30 12 = 360 days.
At about the same time, the
idea of a royal year took precise shape, beginning probably at the time of
barley harvest, when the king celebrated the new (agricultural) year by offering
first fruits to gods in expectation of their blessings for the year. When, in
the course of this year, some royal exploit (conquest, temple building, and so
on) demonstrated that the fates had been fixed favorably by the celestial
powers, the year was named accordingly; for example, as the year in which "the
temple of Ningirsu was built." Until the naming, a year was described as that
"following the year named (after such and such event)." The use of the date
formulas was supplanted in Babylonia by the counting of regnal years in the 17th
The use of lunar reckoning
began to prevail in the 21st century BC. The lunar year probably owed its
success to economic progress. A barley loan could be measured out to the lender
at the next year's threshing floor. The wider use of silver as the standard of
value demanded more flexible payment terms. A man hiring a servant in the lunar
month of Kislimu for a year knew that the engagement would end at the return of
the same month, without counting days or periods of office between two dates. At
the city of Mari in about 1800 BC, the allocations were already reckoned on the
basis of 29- and 30-day lunar months. In the 18th century BC, the Babylonian
Empire standardized the year by adopting the lunar calendar of the Sumerian
sacred city of Nippur. The power and the cultural prestige of Babylon assured
the success of the lunar year, which began on Nisanu 1, in the spring. When, in
the 17th century BC, the dating by regnal years became usual, the period between
the accession day and the next Nisanu 1 was described as "the beginning of the
kingship of PN," and the regnal years were counted from this Nisanu 1.It was
necessary for the lunar year of about 354 days to be brought into line with the
solar (agricultural) year of approximately 365 days. This was accomplished by
the use of an intercalated month. Thus, in the 21st century BC, a special name
for the intercalated month iti dirig appears in the sources. The intercalation
was operated haphazardly, according to real or imagined needs, and each Sumerian
city inserted months at will; e.g., 11 months in 18 years or two months in the
same year. Later, the empires centralized the intercalation, and as late as 541
BC it was proclaimed by royal fiat. Improvements in astronomical knowledge
eventually made possible the regularization of intercalation; and, under the
Persian kings (c. 380 BC), Babylonian calendar calculators succeeded in
computing an almost perfect equivalence in a lunisolar cycle of 19 years and 235
months with intercalations in the years 3, 6, 8, 11, 14, 17, and 19 of the
cycle. The new year's day (Nisanu 1) now oscillated around the spring equinox
within a period of 27 days.
The Babylonian month names were
Nisanu, Ayaru, Simanu, Du'uzu, Abu, Ululu, Tashritu, Arakhsamna, Kislimu, Tebetu,
Shabatu, and Adaru. The month Adaru II was intercalated six times within the
19-year cycle but never in the year that was 17th of the cycle, when Ululu II
was inserted. Thus, the Babylonian calendar until the end preserved a vestige of
the original bipartition of the natural year into two seasons, just as the
Babylonian months to the end remained truly lunar and began when the New Moon
was first visible in the evening. The day began at sunset. Sundials and water
clocks served to count hours.
The influence of the Babylonian
calendar was seen in many continued customs and usages of its neighbor and
vassal states long after the Babylonian Empire had been succeeded by others. In
particular, the Jewish calendar in use at relatively late dates employed similar
systems of intercalation of months, month names, and other details (see below
The Jewish calendar). The Jewish adoption of Babylonian calendar customs dates
from the period of the Babylonian Exile in the 6th century BC.
Other calendars used in the
ancient Near East
The Assyrians and the Hittites.
Of the calendars of other peoples of the ancient Near East, very little is
known. Thus, though the names of all or of some months are known, their order is
not. The months were probably everywhere lunar, but evidence for intercalation
is often lacking; for instance, in Assyria. For accounting, the Assyrians also
used a kind of week, of five days, as it seems, identified by the name of an
eponymous official. Thus, a loan could be made and interest calculated for a
number of weeks in advance and independently of the vagaries of the civil year.
In the city of Ashur, the years bore the name of the official elected for the
year; his eponym was known as the limmu. As late as about 1070 BC, his
installation date was not fixed in the calendar. From about 1100 BC, however,
Babylonian month names began to supplant Assyrian names, and, when Assyria
became a world power, it used the Babylonian lunisolar calendar.
The calendar of the Hittite
Empire is known even less well. As in Babylonia, the first Hittite month was
that of first fruits, and, on its beginning, the gods determined the fates.
At about the time of the
conquest of Babylonia in 539 BC, Persian kings made the Babylonian cyclic
calendar standard throughout the Persian Empire, from the Indus to the Nile.
Aramaic documents from Persian Egypt, for instance, bear Babylonian dates
besides the Egyptian. Similarly, the royal years were reckoned in Babylonian
style, from Nisanu 1. It is probable, however, that at the court itself the
counting of regnal years began with the accession day. The Seleucids and,
afterward, the Parthian rulers of Iran maintained the Babylonian calendar. The
fiscal administration in northern Iran, from the 1st century BC, at least, used
Zoroastrian month and day names in documents in Pahlavi (the Iranian language of
Sasanian Persia). The origin and history of the Zoroastrian calendar year of 12
months of 30 days, plus five days (that is, 365 days), remain unknown. It became
official under the Sasanian dynasty, from about AD 226 until the Arab conquest
in 621. The Arabs introduced the Muslim lunar year, but the Persians continued
to use the Sasanian solar year, which in 1079 was made equal to the Julian year
by the introduction of the leap year.