structural:summarization, information:extraction, information:classification, information:filtering
Alternative chronology

Although the chronology of the Uruk period is full of uncertainties, it is generally agreed to have a rough span of a thousand years covering the period from 4000 to 3000 BC and to be divided into several phases: an initial urbanisation and elaboration of Urukian cultural traits marks the transition from the end of the Ubaid period (Old Uruk), then a period of expansion (Middle Uruk), with a peak during which the characteristic traits of the 'Uruk civilization' are definitively established (Late Uruk), and then a retreat of Urukian influence and increase in cultural diversity in the Near East along with a decline of the 'centre'.