The Uruk period (ca. 4000 to 3100 BC; also known as Protoliterate period) existed from the protohistoric Chalcolithic to Early Bronze Age period in the history of Mesopotamia, after the Ubaid period and before the Jemdet Nasr period. Named after the Sumerian city of Uruk, this period saw the emergence of urban life in Mesopotamia and the Sumerian civilization. The late Uruk period (34th to 32nd centuries) saw the gradual emergence of the cuneiform script and corresponds to the Early Bronze Age; it has also been described as the "Protoliterate period". It was during this period that pottery painting declined as copper started to become popular, along with cylinder seals. Dating and periodization The term Uruk period was coined at a conference in Baghdad in 1930, along with the preceding Ubaid period and following Jemdet Nasr period. The chronology of the Uruk period is highly debated and still very uncertain. It is known that it covered most of the 4th millennium BC. But there is no agreement on the date when it began or ended and the major breaks within the period are difficult to determine. This is due primarily to the fact that the original stratigraphy of the central quarter of Uruk is ancient and very unclear and the excavations of it were conducted in the 1930s, before many modern dating techniques existed. These problems are largely linked to the difficulty specialists have had establishing synchronisms between the different archaeological sites and a relative chronology, which would enable the development of a more reliable absolute chronology. The traditional chronology is very imprecise and is based on some key sondages in the Eanna quarter at Uruk. The most ancient levels of these sondages (XIX–XIII) belong to the end of the Ubaid period (Ubaid V, 4200–3900 or 3700 BC); pottery characteristic of the Uruk period begins to appear in levels XIV/XIII. The Uruk period is traditionally divided into many phases. The first two are "Old Uruk" (levels XII–IX), then "Middle Uruk" (VIII–VI). These first two phases are poorly known, and their chronological limits are poorly defined; many different chronological systems are found in scholarship. From the middle of the 4th millennium, it transitions to the best-known period, "Late Uruk", which continues until around 3200 or 3100 BC. It is in fact in this period that the features which are generally seen as most characteristic of the civilization of the Uruk period