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| | 4th millennium BC - (Site not responding. Last check: 2007-11-07) |
 | | Sumerian city of Ur in Mesopotamia (40th century BC); Sumerian hegemony in Mesopotamia, with the development of writing around the same time as the Indus Valley Civilization, base-60 mathematics, astronomy and astrology, civil law, complex hydrology, the sailboat, the wheel, and the potter's wheel, 4000–2000 BC. |
 | | 3300 BC, only to be discovered in 1991 buried in a glacier of the Ötztal Alps. |
 | | 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. |
| psychcentral.com /psypsych/4000_BC (615 words) |
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