"So he told me a lot of this out of order, since he was kind of refusing to answer any questions until I mentioned the space aliens?"
"So with the aliens - according to him Kaguya was the leader of the aliens who came here, and she married a mortal king, and had twin boys with him. Those kids were Hamura and Hagoromo. Hagoromo was the guy who later became the Sage of Six Paths. Kaguya was betrayed by her husband, though, I think in an 'assassin' way not a 'cheating' way, and she grew bitter about humans. There was a tree, that the Nine Tails called the God Tree, with a fruit, and the tree was sacred and no one could approach it. Kaguya killed the tree's guards and stole the fruit, and when she ate it she got amazing powers. She used those to unite the world and create an era of peace. But when her kids were grown they had the same powers, and she was suspicious of them, and then the kids somehow discovered she was doing evil stuff like feeding sacrifices to the tree? So they decided to stop her, and she got angry at them, and somehow merged with the tree? And became the Ten Tails."
"And then Hagoromo and Hamura fought the Ten Tails, and the fight rearranged the Earth, but they won, and they sealed Kaguya away - though the Nine Tails didn't know where - and split the Ten Tails into the nine Tailed Beasts. Apparently each tail up they're at least twice as powerful, so the Ten Tails was as strong as all of the Tailed Beasts combined."