The "Chicago Syllabary," a cuneiform lexical list of unknown provenance, dating from the first millennium BCE, is thought to contain content compiled earlier in the second millenium.
"The text gives the Sumerian and Akkadian pronunciations of various cuneiform signs along with their names. As such, the text provides unique insights into how the ancients understood and analyzed their languages and the cuneiform script. The list is organized by sign shape. The table consists of two halves, with each half divided into four columns. The first column gives the pronunciations of a given sign and the second column gives the corresponding graph. The third column gives the name of the sign as given by the Babylonian compilers (in some cases a descriptive designation that blends Sumerian and Akkadian), while the fourth column gives the corresponding Akkadian pronunciation. In addition to the importance of its content, the text examplies the development of the cuneiform script in the first millenium BC" (Woods, Teeter, Emberling (eds) Visible Language. Inventions of Writing in the Ancient Middle East and Beyond  No. 60).
The Chicago Syllabary is preserved in The Oriental Institute of the University of Chicago.