The cities of Sumer could not maintain remote, long-distance colonies by military force.
The end of the Uruk period coincided with the Priora oscillation, a dry period from c.
The ancient Sumerian king list recounts the early dynasties.
Like many other archaic lists of rulers, it may include legendary names.
The historical record gradually opens with the Early Dynastic period from ca.
the 29th century , but remains scarce until the Lagash period begins in the 26th century.
The Sumerians were a non-Semitic people and were at one time believed to have been invaders, as a number of linguists believed they could detect a substrate language beneath Sumerian.
However, the archaeological record shows clear uninterrupted cultural continuity from the time of the Early Ubaid period (5200-4500 cal BC) settlements in southern Mesopotamia.
It is fairly certain that it was during the Uruk period that Sumerian cities began to make use of slave labor (Subartu) captured from the hill country, and there is ample evidence for captured slaves as workers in the earliest texts.
Classical Sumer ends with the Akkadian Empire in the 24th century.
Following the Gutian period, there is a brief "Sumerian renaissance" in the 22nd century, cut short in ca.
The principal Sumerian sites (from North to South) were the cities of: Apart from Mari, which lies full 330 km northwest of Agade, but which is credited in the king list to have "exercised kingship" in the Early Dynastic II period, these cities are all in the Euphrates-Tigris alluvial plain, south of Baghdad in what are now the Bābil, Wāsit, Dhi Qar, Al-Muthannā and Al-Qādisiyyah governorates of Iraq.
The Sumerian city states rise to power during the prehistorical Ubaid and Uruk periods.