Sumer is the name for the region of southern Mesopotamia, between the Tigris and Euphrates (modern-day southeastern Iraq and Kuwait), settled during the third millennium b.c.e.

The Sumerians were a non-Semitic people whose place of origin and ethnic identity remains unknown. The Sumerian civilization may have been the first to invent writing. Sumerian early writing, called cuneiform, consisted of drawing pictures on clay tablets with a writing instrument called a stylus.

Originally used to keep economic and administrative records, the art of writing later expanded to include religious texts such as hymns, prayers, and myths. Due to their extreme age, these texts are often not fully understood by modern scholars.

According to some scholars the earliest form of government in Sumer appears to have consisted of something like a primitive democracy with elected leaders who occupied two main offices known as the en and the lugal.

In addition to these leaders, the government had a bicameral legislature consisting of two groups: a council of elders and a body of younger, military-aged men. The offices of the en and the lugal were not hereditary and would later be replaced by kings in the Early Dynastic Period (c. 2900–2300 b.c.e.). During the period of the monarchy the city-state was the main type of government.

Each significant city governed a small amount of territory, which also included smaller towns and villages. Some of the prominent cities include Kish, Lagash, Ur, Uruk, Eridu, and Nippur. Although each city was autonomous and had its own particular deity, the city of Nippur served as the religious center of Sumer.

Between c. 2334 and 2154 b.c.e. the empire of Akkad interrupted Sumerian control of southern Mesopotamia. Founded by Sargon of Akkad and ruled from the city of Akkad, this empire stood for nearly two centuries until it finally succumbed to internal anarchy and external pressure from a foreign people known as the Gutians.

After an interlude of a little over two centuries, the original Sumerian population reasserted itself and regained control c. 2112 b.c.e. The result was the Ur III dynasty, which was governed from the city of Ur. Sometimes called the "Sumerian renaissance", the Ur III period was a reestablishment of Sumerian power and culture.

This Indian summer of the Sumerian civilization featured building programs, the flourishing of the arts and literature, and the emergence of law codes. This revival did not last long, however. After about 100 years the Ur III dynasty fell in 2004 b.c.e., eventually to be replaced by the Babylonians.

Sumer left a lasting impression on the cultures that followed. Some of the inventions the Sumerians contributed include writing, the city-state, the wheel, legal documents, and schools.

Although the language of Sumer is not related to any other known language, it had some influence on Akkadian, the Semitic language that eventually became the dominant language of the ancient Near East. The influence of Sumerian culture, however, continued through the later periods of the Babylonians and the Assyrians in their mythology and historiography.