Fig. 5 Cuneiform inscription. All of the data from Sumer and Babylon comes to us in this form. It is read fluently by many epigraphologists in many institutes of learning and research.  Because of the strategic historic significance of Mespotamia and the length of its history, the quantity of epigraphic material is mountainous.

The writing is done by using a stylus which makes triangular shapes.  The markings are made in soft "green" clay tablets, then kiln baked.  The resulting tablet is good for thousands of years if stored where it cannot break.  Librarians in the days of Sumer and Babylon held almost as much power as the ruler.  This was because they had control of the files.  

Political life is not much different today.  Records can be brought forward which can both destroy or enpower presidents and Generals overnight.  Both Presidents Nixon and Clinton of the USA have experienced this terror.  Times don't really change much.