A. Sutherland – AncientPages.com – The Proto-Elamite script is the world’s oldest system of writing that has yet to be deciphered. This Early Bronze Age writing was briefly in use before the introduction of Elamite cuneiform.
Susa III/ Proto-Elamite cylinder seal with bulls and lion, 3100-2900 BC, Louvre Museum, reference Sb 6166. Source
Later, Elamite cuneiform was adapted from Akkadian Cuneiform and used from c. 2500 to 331 BC. It consisted of roughly 130 glyphs and only a few logograms from Akkadian. Over time, the number of logograms increased, and the writing consists of about 20,000 tablets and fragments. Most of them belong to the Achaemenid Era (730 – 330 BC) and contain mainly financial records.