[2][3][4][5] It is usually assumed that these were the basis for the development of proto-cuneiform, as well as of the contemporaneous Proto-Elamite writing system: as many as two-thirds of the tokens discovered have been excavated in Susa, the most important city in what would become Elam.

[12][13][14][15][16][17] A single fragmentary slab at the Uruk site of Hacınebi Tepe has been proposed as a numerical tablet.

[21] It has been suggested that the development of Proto-cuneiform signs was influenced by symbols (motifs) found on earlier cylinder seals.

Partly spurred by linguistic arguments and evidence, overall it is generally clear that a number of fundamental changes occurred in Mesopotamia—such as the use of the plano-convex brick—at the same time the first definitive evidence of the Sumerian language appeared during the Early Dynastic I period.

Proto-cuneiform offers no clear clues as to what spoken language it encoded, leading to much speculation, though Sumerian is often assumed.

The tablets fall primarily into two styles: the earlier (building level IV) set featuring more naturalistic figures, written with a pointed stylus, and the later set (building level III) with a more abstract style, made using a blunt stylus.

[27][28] Many of the tablets were themselves later used as foundation fill during the construction of the Uruk III Eanna temple complex.

The difficult stratigraphy has brought about a change from referring to tablets based on excavation layer to one of calling them script phase IV and III.

Similarly to the tablets, clay seals previously used to secure vessels and doors ended up in the fill after being removed.

[30] The sites and analysis of sealing has led to suggestions that the tablets originated elsewhere and ended up at Uruk, where they were discarded.

Some have made their way into various private and public collections: the provenance for some can be determined from internal clues, but for some the origin city is unknown.

[39] To decipher an unknown, fully functional writing system, scholars usually need some knowledge of the underlying spoken language, some bilingual texts, and a large corpus.

Proto-cuneiform was not accessible in any of these ways, but decipherment was possible because it was not a full writing system, but a specialized notation for economic administration.

[42] The mathematical system of proto-cuneiform and Proto-Elamite was largely deciphered over a few decades beginning in the 1970s.