What is the name of the language spoken in ancient Sumer?

The language spoken in ancient Sumer was Sumerian.

Sumerian was used in southern Mesopotamia, in an area corresponding mainly to modern-day southern Iraq. It is generally classified as a language isolate, meaning that no proven relationship has been established between it and any other known language family. The earliest clearly identifiable written Sumerian dates to roughly 3100 BC, although earlier proto-writing from the region is harder to assign with certainty.

Sumerian was written in cuneiform, the wedge-shaped script impressed into clay tablets. Early documents record administrative matters such as grain, labor, land, and taxation. Later Sumerian literature included myths, hymns, royal inscriptions, legal texts, and proverbs, including works associated with cities such as Ur, Lagash, and Nippur.

Akkadian gradually became the main spoken language in much of Mesopotamia, but Sumerian did not disappear immediately. It continued as a prestigious scholarly, religious, literary, and administrative language for centuries, much like Latin in medieval Europe. It was used as a classical language into the first millennium BC and possibly as late as the first century AD.