How Predators knew about Earth?

I don't know the legit answer, but after watching Alien vs Predator; I think they used the first human civilizations as slaves for their hunting games against the xenomorphs.

I always liked that about the AvP movie. It was really cool when they used the humans as a sacrifice to create an army of aliens.

Thanks guys, I will have to watch AvP again....

I like AVP and the whole series but they should have used the ancient alien theory but only on a smaller level. To me the Engineers are the real ancient astronauts and the predators to me at least, are the ones that found out later that Earth has humans and lots of bio-diversity. They should have made them like a second generation of the ancient aliens that way it would describe the civilizations of the Americas better because their pyramids are similar. I own all the AVP movies ans all the Predator movies including Prometheus Blu-ray dvd. I collect the NECA action figures to both films also. I am a Fan :-)