The settlement of Sumer, beginning around 5500-3300 BCE, was by West Asian people speaking Sumerian, a unique non-Semitic and non-Indo-European language. Evidence includes names of cities and rivers.^[8] Sumerian civilization developed during the Uruk period (4th millennium BCE), evolving into the Jemdet Nasr and Early Dynastic periods. Eridu, a significant Sumerian city, emerged as a cultural fusion point of Ubaidian farmers, nomadic Semitic pastoralists, and marshland fisher folk, potentially the Sumerians' ancestors.^[9]

The preceding Ubaid period is noted for its distinctive pottery, spread across Mesopotamia and the Persian Gulf. Ubaid culture, possibly derived from northern Mesopotamia's Samarran culture, is characterized by large settlements, mud-brick houses, and the first public architecture temples in Mesopotamia.^[10] This period saw the beginning of urbanization, with developments in agriculture, animal domestication, and the use of ploughs introduced from the north.^[11]

The transition to the Uruk period involved a shift to mass-produced unpainted pottery.^[12] This period marked significant urban growth, the use of slave labor, and widespread trade, influencing surrounding regions. Sumerian cities were likely theocratic, led by priest-kings and councils, including women. The Uruk period saw limited organized warfare, with cities generally unwalled.^[13] The end of the Uruk period, around 3200-2900 BCE, coincided with the Piora oscillation, a climatic shift marking the end of the Holocene climatic optimum.^[14]

The subsequent dynastic period, is generally dated to c. 2900 – c. 2350 BCE, saw a shift from temple-centered to more secular leadership and the emergence of historical figures like Gilgamesh.^[15] It saw the development of writing and the formation of the first cities and states. The ED itself was characterized by the existence of multiple city-states: small states with a relatively simple structure that developed and solidified over time. This development ultimately led to the unification of much of Mesopotamia under the rule of Sargon, the first monarch of the Akkadian Empire. Despite this political fragmentation, the ED city-states shared a relatively homogeneous material culture. Sumerian cities such as Uruk, Ur, Lagash, Umma, and Nippur located in Lower Mesopotamia were very powerful and influential. To the north and west stretched states centered on cities such as Kish, Mari, Nagar, and Ebla.

Eannatum of Lagash briefly established one of history's first empires, encompassing much of Sumer and extending his influence beyond.^[16] The Early Dynastic period was marked by multiple city-states, like Uruk and Ur, leading to eventual unification under Sargon of the Akkadian Empire. Despite political fragmentation, these city-states shared a common material culture.