The pre-Dynastic period of Egypt lasted from about 5,000 BC/BCE to about 3,500 BC/BCE. Before then, human settlements existed all along the Nile River (according to archeological evidence).
The unofficial "Human Era" began around the end of the last major glaciation period, about 12,023 years ago.
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The mere fact that science may not yet adequately explain an object, event, or experience does not mean the immediate explanation should automatically default to a conspiratorial, extraterrestrial, paranormal, or supernatural cause.