Something - we don’t know what - DEFINITELY happened to many hundred tribes and civilizations all about the same time - but far enough back that the living people who wrote it down repeat the same events as stories, not eyewitness accounts.
Discovery/TLC/History Channel had a recent report on this: claim most likely event is a comet/asteroid impact off Madasgascar with wavews wiping out people in Africa, Carib, south Persian coasts, India, Australia, Borneo, Malaysia, etc.
Thanks for the ping, Bob. Free via Open Access: Full Text (PDF)