There were several different civilizations in ancient Mesopotamia at different times, including Akkad,Assyria,Bablon and Sumeria.Improvement: Uruk, Ur, Sippar, Lagash, Nippur.
Firstly a myth is a story made up because there is no known or understood natural answer at the time, ie primitive peoples did not understand natural causes and made up a story to explain th unknowns. Now of course we have a rapidly increasing scientific understanding of how and why, so the way to deal with a myth is simply to state what actually happens. For example the creation myth is replaced by things like the big bang theory, the creation of man by evolution, and so on. Really easy stuff, because a myth is a made up story, it can't stand up to fact. What needs to be kept in mind is that there is a second level - legend, which is a traditional story, widely held to be true. As these legends have been built up as folklore, they have to be addressed by historical research - literature, plays, historical accounts, official records, diaries, pottery, frescoes, archaeological and geological methods and so on. The effectiveness of such reconstructions is dependent on the quality of the reference materials and the objectivity and ability of both the originators and the persons trying to interpret them.