The unique language of the Sumerians, the titular founders of civilization, seems to be unrelated to any other known language, defunct or otherwise.

Who they were, and how their civilization sprang forth, remains a mystery.

The Kish tablet, a limestone tablet found at Tell al-Uhaymir, Babil Governorate, Iraq—the site of the ancient Sumerian city of Kish, is dated to around 3500 BCE (middle Uruk period).

A plaster cast of the artifact is today in the collection of the Ashmolean Museum, Oxford.

The Kish tablet is inscribed with proto-cuneiform signs, and may be considered the oldest known written document.

The writing is, however, still purely pictographic, and represents a transitional stage between proto-writing and the emergence of the partly syllabic writing of the cuneiform script proper.

The "protoliterate period" of Egypt and Mesopotamia is taken to span about 3500 to 2900 BCE.

The Kish tablet is thus more accurately identified as the first document of the Mesopotamian protoliterate period.