<P> Around 10,200 BC the first fully developed Neolithic cultures belonging to the phases Pre-Pottery Neolithic A ( PPNA ) and Pre-Pottery Neolithic B ( 7600 to 6000 BC ) appeared in the fertile crescent and from there spread eastwards and westwards . One of the most notable PPNA settlements is Jericho in the Levant region , thought to be the world 's first town ( settled around 8500 BC and fortified around 6800 BC ) . In Mesopotamia , the convergence of the Tigris and Euphrates rivers produced rich fertile soil and a supply of water for irrigation . The civilizations that emerged around these rivers are among the earliest known non-nomadic agrarian societies . It is because of this that the fertile crescent region , and Mesopotamia in particular , are often referred to as the cradle of civilization . The period known as the Ubaid period ( c. 6500 to 3800 BC ) is the earliest known period on the alluvial plain , although it is likely earlier periods exist obscured under the alluvium . It was during the Ubaid period that the movement towards urbanization began . Agriculture and animal husbandry were widely practiced in sedentary communities , particularly in Northern Mesopotamia , and intensive irrigated hydraulic agriculture began to be practiced in the south . Eridu is the oldest Sumerian site settled during this period , around 5300 BC , and the city of Ur also first dates to the end of this period . In the south , the Ubaid period had a very long duration from around 6500 to 3800 BC ; when it is replaced by the Uruk period . </P>
where is the oldest civilization known to man
Mesopotamia