How Does Madara Know About the 10-Tails?
It seems like all of the Kages had no idea that the 10-tails ever existed. Madara, on the other hand, appeared to be lecturing them on the history of the 10-tails and how the Sage of the Six Paths went to the trouble of sealing it within himself, dividing its chakra up into the tailed beasts we know and love today, and entombing its physical remains in what became the moon.
So, my question is: How does Madara know all of this?! Sure, Madara's been around for a while, and he knows a lot of stuff, but how does he know something so pivotal and so important to the existence of the tailed beasts when no one else seems to know it? I mean, that story is so epic that one would think that people would remember it. But, it seems Madara is the only one who knows it.
Is it solely because Madara is really old that he knows about it? Because one would think that if Madara's generation was familiar with the story, then they would pass the story down to the next generation, and so on. Or is it because Madara has access to some sort of ancient text? Or is there no explanation, and Kishi is just having Madara say this to move the plot along? Or is Madara perhaps lying?
I don't know.