SORU: boş bırakılan yere parçanın anlam bütünlüğünü sağlamak için getirilebilecek cümleyi bulunuz
Between 4000 and 2000 BC, the first urban civilizations arose independently along the Tigris, the Nile, the Indus and the Yellow River. All of these great rivers are prone to seasonal variations in flow, with flood alternating with drought. ---- Once this technology was developed, farmers found that they could move into drier areas, such as southern Mesopotamia.
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Archaeologists have found sites where one Sumerian city was built on top of an earlier one, separated by a layer of mud swept over in a flood. |
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Although most humans lived in small hunting bands, some pre-farming peoples worked out a very different strategy of survival. |
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To maximize agricultural production, it was necessary to build dams to store the flood waters in reservoirs to water the fields during the dry season. |
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Constructing such schemes required an accurate calendar to predict when the floods would come, and a high degree of social organization. |
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It was here that first people first began to cultivate crops, kick starting a global revolution in the way humans live |