The Lunar Calendar was made because of the observation of the shifts in the moon cycle. As a very religious place the need for planning was very important which is why the Lunar Calendar was invented. When there was a religious event they would be prepared for it. Another reason it was necessary for the Mesopotamian people to make this change was the fact that most of Mesopotamia was located around the Tigris and Euphrates rivers. With the lunar calendar they could track when the dry seasons would occur and when the rivers would flood. As a polytheistic group with more than 2,100 gods the need for the Lunar Calendar to help organize the religious days was important.

There were not very many downsides to the Lunar Calendar because of its practical features, other that that it was on a 365 day calendar, meaning that after that year was finished the calendar was then put off a day for the next 365 day cycle. The Lunar Calendar was not especially easy to use as you would have to get taught by the previous philosophers, but once you understood the concept of it, using the lunar calendar was not difficult.