Um wow. Normally this kind of stuff has no proof or anything but the History channel has really outdone themselves they actually have managed to compile some damn convincing/freaky/spooky evidence of aliens visiting the earth in the early days of human culture.
Now I know I have an overly active imagination, but I am a scientist at hart and I take everything with a grain of salt and take care not to get carried away with concepts like this particularly because I am a skeptic of anything this outrageous.
But here is the thing I looked at everything they have said, so far the most convincing thing was some African culture with a legend of their god coming to them from a specific star, which is invisible to the naked eye and basic telescopes oh and did I mention this legend goes back way farther then the discovery of that star by science, which I'm sorry is just plain freaky.
Here is the other convincing part. All these myths they mention go something like this, people who are lacking culture or away of life are visited by people from the sky who then help them, giving them culture, basic technology, stuff like that, (or it's a creation myth). Plus all the little details that make the stuff they are talking about seem actually plausible.
Not saying they are right, not saying they are wrong, but they have compiled some very interesting facts.
Oh and P.S. history Channel get your minds out of the gutter! the chance of a being from another planet, let alone another solar system, being able to successfully reproduce with a human seem uh I don't know like maybe one in say 100,000,000,000,000,000,000,000,000,000,000,000,000,000!!!! I mean come on! their reproductive system most likely wouldn't even resemble or function like ours do.
Oh and P.P.S. you might want to decide weather you want to depict the aliens as people in space suits or as human looking beings that freely interacted with us earthlings. You went back and forth quite a few times. Again almost no reason to suspect they would strongly resemble us, although there is a theory about how since humanoid worked here it is therefore a successful design and more likely to reach a similar dominance in other planets evolutionary development.