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| | The Dispatch - Serving the Lexington, NC - News (Site not responding. Last check: 2007-11-05) |
 | | Sumerian city of Ur in Mesopotamia (4th century BC); Sumerian hegemony in Mesopotamia, with the development of writing, base-60 mathematics, astronomy and astrology, civil law, complex hydrology, the sailboat, the wheel, and the potter's wheel, 4000–2000 BC. |
 | | Beginning of desertification of Sahara (35th century BC). |
 | | The shift by the Sahara Desert from a habitable region to a barren desert. |
| www.the-dispatch.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=4th_millennium_BC (865 words) |
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