system
Given the following post, respond as if you're commenting on Reddit:
human
[Predator] How long have the predators seen Earth as prime hunting grounds? How long have they hunted humans in particular?

So, going by the fact that both the Predator and AVP film universes have the predators fighting the xenomorphs as some of their “ultimate prey” despite xenomorphs being simple animals, we know predators will gladly hunt non-sapient species that happen to be tough to bring down. Predator civilization also seems to be much older than human civilization, and predators are said to live for hundreds of years at the least. Given all this, how long have the predators been traveling to Earth, and how old are their species potentially? Are they old enough to have traveled to Earth during the heyday of the dinosaurs and maybe go on a good old-fashioned Tyrannosaurus hunt (after all, Mesozoic Earth was the tropical conditions they prefer anyway)? Did they not find Earth until some time during the Cenozoic maybe? Are humans what they’ve always gone to Earth for and they didn’t get interested in the planet until humans had evolved? How long have they been hunting humans for at any rate? Cavemen were as intelligent as modern humans, just with less knowledge, they had the same intellectual capabilities as us, could plan and adapt to new situations, etc., and predators are shown to enjoy a good melee fight. Do you think the predators would throw down with the greatest warrior in a prehistoric tribe perhaps? Or did they wait until states developed with full-fledged armies who had developed martial philosophies and could understand the Predators as fellow warriors? 

Or, (controversial) were humans totally irrelevant to them until we developed bombs and assault rifles?
gpt
It's unclear when the Yautja originally came to earth. It's theorized to have happened at least 10,000 years ago but only in the avp film continuity. Novel and comics continuity it appears to be similar but without any concrete information like the pre-sumarian civilization in Antarctica. Earth was for a long time treated as a lesser hunting ground with ice age animals hunted sparingly by younger hunters. The predators either uplifted humans to act as hosts for xenomorph hunts or eventually humans proved themselves as worthy game with metal weapons. The earliest known human hunt is from around the 1600s but evidence does point to earlier hunts in the mid 1200s to 1300s without much substantial evidence. That said different clans have different tastes in prey so some have abandoned earth as mega fauna went extinct and others have exclusively used it for Xenomorph hunts and others still only to hunt humans as we have developed. It's not until the late 1800s that predators began seeking out humans for prey after several humans killed or grievously wounded hunters proving themselves as challenging game instead of just dangerous when predators were handicapped.