What Science Has Learned about the Rise of Urban Mesopotamia
The Uruk period in Mesopotamia, also called the Sumerian state, is what archaeologists call the first great blossoming of Mesopotamian society, when the great cities throughout Mesopotamia, including Uruk in the south, but also Tell Brak and Hamoukar in the north, expanded into the world's first metropolises. The Uruk period lasts between approximately 4000-3000 BC, and it is split into Early and Late Uruk about 3500 BC.
Tells and the Rise of the First Urban Communities
The really ancient cities in Mesopotamia are within tells, great mounds of earth built up from centuries or millennia of building and rebuilding on the same place. Further, much of southern Mesopotamia is alluvial in nature: lots of the earliest sites and occupations at later cities are currently buried under meters and meters of soil and/or building rubble, making it difficult to say with absolute certainty where the location of first or earliest occupations occurred. Traditionally, the first rise of ancient cities is attributed to southern Mesopotamia, in the alluvial marshes above the Persian gulf.
However, some fairly recent evidence at Tell Brak in Syria (Oates et al., Ur et al) suggests that its urban roots are somewhat older than those in the South. The initial phase of urbanism at Brak occurred in the late fifth to early fourth millennium BC, when the site already covered 55 hectares (135 acres). The history, or rather prehistory of Tell Brak is similar to the south: an abrupt variation from the earlier small settlements of the preceding Ubaid period.
It is undoubtedly the south which still currently shows the bulk of the growth in the early Uruk period, but the first flush of urbanism seems to have come from northern Mesopotamia.
Early Uruk [4000-3500 BC]
The Early Uruk period is signaled by an abrupt change in settlement pattern from the preceding Ubaid period [6500-4200 BC]. During the Ubaid period, people lived primarily in small hamlets or one or two largish towns, across an enormous chunk of the western Asia: but at the end of it, a handful of communities began to enlarge.
The settlement pattern developed from a simple system with large and small towns to a multi-modal settlement configuration, with urban centers, cities, towns and hamlets by 3500 BC. At the same time, there was a sharp increase in the total number of communities overall, and several individual centers swelled to urban proportions. By 3700 Uruk was already between 70-100 ha (175-250 ac) and several others, including Eridu and Tell al-Hayyad covered 40 ha (100 ac) or more.
Pottery of the Uruk period included undecorated, plain wheel thrown pots, in contrast to the early Ubaid hand made painted ceramics, which probably represents a new form of craft specialization. One type of ceramic vessel form that first shows up in Mesopotamian sites during the Early Uruk is the bevel-rimmed-bowl, a distinctive, coarse, thick-walled and conical vessel. Low-fired, and made of organic temper and local clay pressed into molds, these were clearly utilitarian in nature. Several theories about what they were used for include yogurt or soft cheese manufacture, or possibly salt making. On the basis of some experimental archaeology, Goulder argues these are bread-making bowls, easily mass-produced but also made by home bakers on an ad hoc basis.
Late Uruk [3500-3000 BC]
Mesopotamia diverged sharply about 3500 BC, when the southern polities became the largest in Mesopotamia and began colonizing Iran and sending small groups into northern Mesopotamia. One strong piece of evidence for social turmoil at this time is the evidence of a huge organized battle at Hamoukar in Syria.
By 3500 BC, Tell Brak was a 130 hectare metropolis; by 3100 BC, Uruk covered 250 hectares. Fully 60-70% of the Mesopotamian population lived in towns (10-15 ha), small cities (25 ha, such as Nippur) and larger cities (50 ha, such as Umma and Tello).
Why Uruk Blossomed: The Sumerian Takeoff
There are several theories about why and how the great cities grew to such a large and truly peculiar size and complexity compared to the rest of the world. Uruk society is typically seen as a successful adaptation to changes in the local environment--what had been a marshland in southern Iraq was now arable lands suitable for agriculture. During the first half of the fourth millennium, the southern Mesopotamian alluvial plains had substantial rainfall; populations may have flocked there for the great agriculture.
In turn, the growth and centralization of population led to the need for specialized administrative bodies to keep it organized. The cities might have been the result of a tributary economy, with the temples the recipients of tributary from self-sufficient households. Economic trade might have encouraged the specialized production of goods and a chain of competition. Waterborne transportation made possibly by reed boats in southern Mesoptamia would enabled social responses that drove the "Sumerian Takeoff".