Board Thread:Theories and Speculation/@comment-28819877-20170801141801/@comment-734582-20170801171732

LovelyFox wrote: it's still a great failure. Some events of real world have been discovered even before existing of mankind itself, not to mention the history of mankind. Not of people though. We only know about certain people because of written text, yet we've not really seen anyone focused on keeping track of history that way. Hagoromo's existence was passed on through legend only, Ashura and Indra were completely wiped from history. Plus, this assumes Black Zetsu didn't destroy what little evidence existed.

Lastly, evidence of Kaguya's existence does exist, but it is not in our space-time. So it wouldn't have been found anyway.