Sumer was the first urban civilization in the historical region of southern Mesopotamia, modern-day southern Iraq, during the Chalcolithic and Early Bronze ages, and arguably the first civilization in the world with Ancient Egypt. Living along the valleys of the Tigris and Euphrates (Mesopotamia is Greek for the land between two rivers), Sumerian farmers were able to grow an abundance of grain and other crops, the surplus of which enabled them to settle in one place.
Proto-writing in the prehistory dates back to c. 3000 BC. The earliest texts come from the cities of Uruk and Jemdet Nasr and date back to 3300 BC; early cuneiform writing emerged in 3000 BC.
Modern historians have suggested that Sumer was first permanently settled between c. 5500 and 4000 BC by a West Asian people who spoke the Sumerian language (pointing to the names of cities, rivers, basic occupations, etc., as evidence), an agglutinative language isolate.
These conjectured, prehistoric people are now called “proto-Euphrateans” or “Ubaidians”, and are theorized to have evolved from the Samarra culture of northern Mesopotamia ). The Ubaidians (though never mentioned by the Sumerians themselves) are assumed by modern-day scholars to have been the first civilizing force in Sumer, draining the marshes for agriculture, developing trade, and establishing industries, including weaving, leatherwork, metalwork, masonry, and pottery.
Reliable historical records begin much later; there are none in Sumer of any kind that have been dated before Enmebaragesi (c. 26th century BC). The Sumerians were settled along the coast of Eastern Arabia, today’s Persian Gulf region, before it flooded at the end of the Ice Age. (May be the origins of the flood myth i.e Noah)

Sumerian civilization took form in the Uruk period (4th millennium BC), continuing into the Jemdet Nasr and Early Dynastic periods. During the 3rd millennium BC, a close cultural symbiosis developed between the Sumerians, who spoke a language isolate, and Akkadian-speakers, which included widespread bilingualism. Sumerian culture seems to have appeared as a fully formed civilization, with no pre-history.
The influence of Sumerian on Akkadian (and vice versa) is evident in all areas, from lexical borrowing on a massive scale, to syntactic, morphological, and phonological convergence. This has prompted scholars to refer to Sumerian and Akkadian in the 3rd millennium BC as a Sprachbund.[14] Sumer was conquered by the Semitic-speaking kings of the Akkadian Empire around 2270 BC (short chronology), but Sumerian continued as a sacred language.
Native Sumerian rule re-emerged for about a century in the Neo-Sumerian Empire or Third Dynasty of Ur (Sumerian Renaissance) approximately 2100-2000 BC, but the Akkadian language also remained in use. The Sumerian city of Eridu, on the coast of the Persian Gulf, is considered to have been the world’s first city, where three separate cultures may have fused — that of peasant Ubaidian farmers, living in mud-brick huts and practicing irrigation; that of mobile nomadic Semitic pastoralists living in black tents and following herds of sheep and goats; and that of fisher folk, living in reed huts in the marshlands, who may have been the ancestors of the Sumerians