Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia, modern-day southern Iraq, during the Chalcolithic and Early Bronze ages, and one of the first civilizations in the world along with Ancient Egypt and the Indus Valley. Living along the valleys of the Tigris and Euphrates, Sumerian farmers were able to grow an abundance of grain and other crops, the surplus of which enabled them to settle in one place. Prehistoric proto-writing dates back before 3000 BC. The earliest texts, from c. 3300 BC, come from the cities of Uruk and Jemdet Nasr; early cuneiform script emerged around 3000 BC.
Proto-writing
The transition from proto-writing to the earliest fully developed writing systems took place in the late 4th to early 3rd millennia BCE in the Fertile Crescent.
The Kish tablet, dated to 3500 BCE, reflects the stage of "proto-cuneiform", when what would become the cuneiform script of Sumer was still in the proto-writing stage. 
By the end of the 4th millennium BCE, this symbol system had evolved into a method of keeping accounts, using a round-shaped stylus impressed into soft clay at different angles for recording numbers. This was gradually augmented with pictographic writing using a sharp stylus to indicate what was being counted. 
The transitional stage to a writing system proper takes place in the Jemdet Nasr period (31st to 30th centuries BCE).
A similar development took place in the genesis of the Egyptian hieroglyphs. Various scholars believe that Egyptian hieroglyphs "came into existence a little after Sumerian script, and ... probably [were] ... invented under the influence of the latter ...", although it is pointed out and held that "the evidence for such direct influence remains flimsy" and that "a very credible argument can also be made for the independent development of writing in Egypt ..." (See further Egyptian hieroglyphs).