Bronze Age
Bronze Age cultures differed in their development of the first writing. According to archaeological evidence, cultures in Mesopotamia (cuneiform script) and Egypt (hieroglyphs) developed the earliest viable writing systems.
The overall period is characterized by widespread use of bronze, though the place and time of the introduction and development of bronze technology were not universally synchronous. Human-made tin bronze technology requires set production techniques. Tin must be mined (mainly as the tin ore cassiterite) and smelted separately, then added to molten copper to make bronze alloy. The Bronze Age was a time of extensive use of metals and of developing trade networks (See "Tin sources and trade in ancient times"). A 2013 report suggests that the earliest tin-alloy bronze dates to the mid-5th millennium BC in a Vinča culture site in Pločnik (Serbia), although this culture is not conventionally considered part of the Bronze Age. The dating of the foil has been disputed.
Cradle of civilization
Sumerian civilization coalesces in the subsequent Uruk period (4000 to 3100 BC). Named after the Sumerian city of Uruk, this period saw the emergence of urban life in Mesopotamia and, during its later phase, the gradual emergence of the cuneiform script. Proto-writing in the region dates to around 3500 BC, with the earliest texts dating to 3300 BC; early cuneiform writing emerged in 3000 BC. It was also during this period that pottery painting declined as copper started to become popular, along with cylinder seals. Sumerian cities during the Uruk period were probably theocratic and were most likely headed by a priest-king ("ensi"), assisted by a council of elders, including both men and women. It is quite possible that the later Sumerian pantheon was modeled upon this political structure. Uruk trade networks started to expand to other parts of Mesopotamia and as far as North Caucasus, and strong signs of governmental organization and social stratification began to emerge leading to the Early Dynastic Period (c. 2900 BC). The Jemdet Nasr period, which is generally dated from 3100–2900 BC and succeeds the Uruk period, is known as one of the formative stages in the development of the cuneiform script. The oldest clay tablets come from Uruk and date to the late fourth millennium BC, slightly earlier than the Jemdet Nasr Period. By the time of the Jemdet Nasr Period, the script had already undergone a number of significant changes. It originally consisted of pictographs, but by the time of the Jemdet Nasr Period it was already adopting simpler and more abstract designs. It is also during this period that the script acquired its iconic wedge-shaped appearance. At the end of the Jemdet Nasr period there was a major archaeologically attested river flood in Shuruppak and other parts of Mesopotamia. Polychrome pottery from a destruction level below the flood deposit has been dated to immediately before the Early Dynastic Period around 2900 BC.