It was recently confirmed by an ice core research that planetary-scale climate changes occur every 12k years. The last such change has still remained in our history under different names like Great Flood. Of course, changes of this scale have erased most of the traces of the earlier civilizations. But there are still many to find starting with the Baalbek megaliths, for instance. And not mentioning the traces that remained in our culture: Sumerian and Greek Mythology, Old Testament, etc. Vajra / Zeus lightnings, Vimana / chariots of Greek gods, and many others. What we perceive as myths and naive beliefs of our predecessors are essentially artifacts of this previous civilization. And nothing godlike or holy about them, just a bunch of advanced technologies turned into myths over the centuries.