The heavens, maybe? I was reading this article, and I was reminded of one of my favorite pet theories. And just ignore all of the time estimates in the article. Whenever I hear some science nerd blabbing about ' hundreds of millions of years', I just hold out my palm and say 'talk to the hand'.
My old timers know about this, but for my new readers, I'll just flat out tell you that I believe humanity was created by God on Mars. I think that is where the Garden is/was. Put a human in a cave, with no timepieces, and they will revert to Martian time very quickly. We are hard-wired for it.
How we got to Earth, I have no idea, but I suspect that it was shortly after Adam and Eve were cast from the Garden. I believe that what we call 'Atlanteans' were actually Adamites, very advanced, brilliant, with technology that looked like magic. I suspect that Cain was banished from Mars for his crime of fratricide, and transported by angels to Earth.
I suspect that his parents missed their only son so much, they found a way to join him there. The Bible says that there was a full-blown society that Cain went out into it, and a mark was put upon him, so that no man would harm him. Could harm him? I think Cain was the first vampire. I think he bred with Adam's first wife Lilith, and their offspring have been bedeviling us since.
And some of us, the Dhampir, still carry a portion of his essence inside us...
Anyway, there was a war in the heavens, and Earth won. It was kind of a Heinleinesque 'Moon Is A Harsh Mistress' scenario, with both sides using ammo scrounged from various asteroid fields. Look at the moon. Have you ever seen photos of the DMZ in Viet Nam, when the B-52's were busy? Yep. And we had a large moon that could be kept between us and them, with low enough gravity to make launching things from its surface a relatively simple proposition.
Oh, they got their licks in on us. Go back and look at those pictures in the linked article.
But we hammered them and hammered them until we tore their atmosphere away, and their planet looked like a damn golf ball.
Did they sue for peace? Beg for a place to settle on our little blue ball? I dunno, I left my psychic powers in my other pants.
That's for another day. I'm bored. I just report...