I am not really a history buff, but some times it pays to keep track of some of this stuff. My guess is a lot longer than what is recorded on clay tablets, but just a guess. I think China has a longer recorded history, but Euro centrict anglos don't try to keep track of them. Think it has do what which end of the barrel of gun you look down.
http://it.stlawu.edu/~dmelvill/mesomath/history.htmlBrief History of Mesopotamia
Mesopotamia, the land between the rivers, derives its name and existence from the rivers Tigris and Euphrates. These two rivers created the Fertile Crescent in the midst of surrounding inhospitable territory. The space we call Mesopotamia is roughly the same as that of the modern country of Iraq.
About ten thousand years ago, the people of this area began the agricultural revolution. Instead of hunting and gathering their food, they domesticated plants and animals, beginning with the sheep. They lived in houses built from reeds or mud-brick, grouped in villages where they tended their crops. They built granaries to store their grain, and they began developing a token system to record trade and accounts.
Between 3500 and 3000, for reasons still not well understood, the civilization of Southern Mesopotamia underwent a sudden growth and change, centered in the cities of Ur and Uruk. This development was perhaps driven by climatic change which rendered the old ways of agriculture less productive. People clustered into fewer, but larger, locations and the plough, potter's wheel and the introduction of bronze can be seen as responses to the demands of a more intensive economic life, and also as causes of increased complexity in that life. In this same period came the beginnings of writing, metrological systems and arithmetic.
The main part of the third millennium, now called the Early Dynastic period, saw the gradual development of Sumerian civilization, based on numerous city states. From the Early Dynastic period comes the earliest Sumerian literature, including the epic poetry about Gilgamesh. The Sumerians lived in a complex, unpredictable and frequently hostile environment. They had to contend with floods, droughts, storms, dust, heat, disease and death. They strove to uncover order and organization in the world to overcome feelings of futility and powerlessness.
The Early Dynastic period was brought to an end when Sargon (2334-2279) created the world's first empire, stretching the length and breadth of the fertile crescent. The impact of Sargon's unification of Sumer and Akkad resonated down through the history of Mesopotamia for the next two thousand years.
The Sargonic empire lasted for almost a hundred and fifty years, before it fell to insurrections and invasions. There followed a characteristically Mesopotamian turbulent period, part of which involved the hordes of Guti, who ruled in the south for a century or so. Eventually, they were thrown out in an uprising which inaugurated the Third Dynasty of Ur (Ur III, or Neo-Sumerian period). During the reign of the Ur III kings beginning with Ur-Nammu and Shulgi, Sumerian culture and civilization experienced a remarkable renaissance. There was peace and prosperity throughout the land, the legal system was strengthened, the calendar was revised, metrology simplified, agriculture revived, and towns and temples were rebuilt, the most imposing of the latter being the ziggurat at Ur.
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