Sumer is the first known civilization in the ancient province of southern Mesopotamia (south-central Iraq), originating during the 6th and 5th millennia BC during the Chalcolithic and Early Bronze Ages. Along with ancient Egypt, the Caral-Supe culture, the Indus Valley civilization, the Minoan civilization, and ancient China, it is one of the globe's early civilizations. Sumerian farmers who lived in the Tigris and Euphrates valleys cultivated a surplus of wheat as well as other products, which allowed them to establish urban towns. Before 3000 BC, there was proto-writing. The oldest manuscripts date from between 3500 and 3000 BC and are from the towns of Uruk and Jemdet Nasr.

During the ancient Ubaid and Uruk eras, Sumerian city-states came to dominance. Sumerian recorded history dates back to at least the 27th century BC, but the historical evidence was largely unknown till the Early Dynastic III period, around the 23rd century BC, when a now-deciphered syllabary typing project is developed, allowing archaeologists to review emerging documents and manuscripts. In the 23rd century BC, the Akkadian Empire was the first power to effectively combine significant sections of Mesopotamia. Following the Gutian period, the Ur III monarchy unified south and north Mesopotamia in the same way. At the start of the second millennium BC, it came to an end due to Amorite raids. The Amorite 'dynasty of Isin' lasted until Mesopotamia was unified under Babylonian power around 1700 BC. The Sumerians were assimilated into the Akkadian (Assyro-Babylonian) people throughout time.