Vanished ancient human civilizations 

Readings on the ancients seem replete with accounts of some personages that aparently were actually knowledgeable of repeated very massive or cataclysmic disasters that could have happened to civilizations that were much more ancient. The doomed civilizations were the really ancient types that could have existed much earlier than the 4,000_B.C. considered as beginning of current civilization, or before our recorded written history (prehistoric).

Such old events may no longer be within reasonable verification means for the average reader, if not of any current entity even in our modern age, although veracity may reasonably be weighed from the sophistication of told details.

A priest of Egypt who conversed (or argued) with a high government official of Athens involved with law (a lawyer type) did hint of repeated annihilation on humanity, as reported by ancient Plato (ref.#pe2). Plato was a Greek philosopher who lived around 427_B.C.to 347_B.C. (ref.#pg2)..