[fr_freak]

It’s an insult to those peoples to conclude that a flying saucer must have showed up and done it for them.

For the more whimsical takes on history, I prefer the theory that 12,000 years ago a major global catastrophe wiped out some pretty advanced civilizations who may have been the true builders of things like the pyramids, and the Egyptians only found them. And, perhaps, some remnants of those civilizations managed to survive and are actually the ones driving the UFOs.

[DesertRhino]

I would be open to the idea that some fairly advanced civilizations did exist before the last ice age, and what we see now is a human resurgence after the glaciers receded.
But nobody is flying UFOs out there... nobody.