Ubaid Proto-Civilization

I'm pretty interested in the past history of civilizations.  While modern civilization is different in important ways from older civilizations, it's unlikely to be different in all ways, and so understanding the rise and fall of other civilizations provides potentially useful data-points as to the general nature of the beast.

So I was pleased by an article in the New York Times yesterday which provided an introduction to work by some archeologists on the Ubaid proto-civilization, which was a precursor to the Sumerian civilization in southern Iraq.  In particular, it describes the beginning of an excavation of Tell Zeidan, one of the larger and better preserved Ubaid sites.  Poking around at the website of the Oriental Institute of the University of Chicago, I found this portion of their annual report, which gave me more of the detail I usually crave when reading a newspaper article.  The following discussion is mainly drawn from that document - the Wikipedia, as usual, also already knows something about the subject.

The Ubaid period is from about 5500BC to about 4000BC, and thus before any known full civilization.  The map above shows the extent of settlements with Ubaid influence - an enormous area from Southern Iraq to Northern Syria.  Note that these people did not have horses (although they probably invented the potter's wheel, and may have been the inventors of the wheel as a transport device).

The commonality of these sites is as determined, for example, by the style of pottery found in archaelogical excavations:

as well as other elements of material culture (copper smelting implements, stamp seals, etc).  Given the map above, Ubaid culture clearly extended over a large area - whether this represents an empire of some kind or a looser trading network is unclear.

I wanted to know how big these settlements were to get a better feeling for the society.  The Tell Zeidan site was thought to be comparable in size to other major Ubaid settlements, and the extent of it is mapped as follows:

The following shows Tell Zeidan approximately superimposed on modern day San Francisco:

The whole of Tell Zeidan is about the size of the financial district.   Given that San Francisco's population is 800,000, Tell Zeidan's population must have been of the order of magnitude of a few thousand to a few tens of thousands at the absolute outside.  In other words, Tell Zeidan is a bit more than a village, by modern standards, more like a very small town.  So presumably Ubaid society should be seen as a network of villages and small towns (supported by irrigated agriculture).  There is sign of specialist artisans (pottery, copper smelting), but some technology was neolithic (for example, there are flint sickle blades everywhere, indicating grain was harvested with stone tools and human labor).

Fascinatingly, Tell Zeidan was continuously occupied for around 2000 years (from about 5800BC to 3800BC) with no sign of destruction layers during that period, so societal arrangements must have been quite stable. This discussion also suggests that there is no evidence of warfare during the Ubaid period.