A
calendar based in 12 months each starting on
new moon. This gave the
Babylonians problems regarding when the planting season started. For this reason an extra month was added after the 12th - this was very random for several hundred years - and it wan't until somewhere betwen 500 and 380 BCE, that the
Persians noticed that adding seven intercalary
months every 19 years kept the lunar calendar from straying from the solar. (Which is still very unprecise)
The
New Year began in the
Spring and was marked by a
festival of approximately twelve days, which included the ritual
sacrifice of a sheep whose head was then removed to the
wilderness presumably to cleanse the community of
elemental chaos.