Folklore

Folklore is one of the most ancient stories that actually has a based but lack the evidence to proof itself as the right event in history. More that we know about this type of legend that it only based on a tale story which means that it doesn't has any written proof attached to it. Folklore spread from one person to the other through a speaker to the other speaker. So the original story might just been altered through many different culture inherited by the speaker. Those changes might just be incomprehensible to the original tellers through those cultural effect to the story itself. 

There are many folklore in these world that cannot be understand by other society or culture just because the difference of these culture is just to much. And the fact these story emerges from one society without any effect of outsider story made these folklore just beyond the comprehensible of any person that doesn't belong to the society which it belongs to.