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| | 4th millennium BC (Site not responding. Last check: 2007-10-26) |
 | | Sumerian city of Ur in Mesopotamia (40th century BC); Sumerian hegemony in Mesopotamia, with the invention of writing, base-60 mathematics, astronomy and astrology, civil law, complex hydrology, the sailboat, the wheel, and the potter's wheel, 4000–2000 BCE. |
 | | According to Hindu mythology, the Epoch of the Kali Yuga occurred at midnight (00:00) on 18 February 3102 BC, the traditional death of Krishna |
 | | Based on studies by glaciologist Lonnie Thompson (professor at Ohio State University and researcher with the Byrd Polar Research Center) [1] a number of indicators shows there were a global change in climate 5,200 years ago: |
| www.punweb.com /article/4th_millennium_BC (485 words) |
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