The Killer Folk were a posthuman species that evolved from the Human Predators.
The evolution of sapience went hand in hand with the reduction of the thumb claws and saber teeth of the Predators, which are still present, but smaller and more fragile. Regardless, the Killer Folk still had predatory urges, which showed in their religions.
Their religions almost always centered around the art of hunting and war, with frequent orgies of violence and sex being part of their lifestyles. The best hunters and warriors were seen as nobility, and nomadic warriors gathered annually to hunt their life-stock, domesticated from their former human prey.
In an industrial revolution, one nation-pack of Killer Folk developed factory farming, organized state structure, secularism and new technologies, and the entire population got divided into progressive factory herders and conservative hunting states. This almost led to world wars more than once, but the Killer Folk managed to survive and unite again.
With this history, the world of the Killer folk has more buried dark ages, ruined cultures and fallen kingdoms than any other world. Eventually, through radio communication, they made contact with the Satyriacs and together they founded the Second Galactic Empire, which was soon joined by the Tool Breeders.
During the following ten million years, other posthumans joined in on the communications, including the Modular People, Pterosapiens and Asymmetrics. After another 20 million years, the empire also included the Saurosapients, Snake People, Symbiotes and the Sail People. Only after fourty million years, the Bug Facers joined in.
Over a timespan of about 80 million years, the Second Empire developed, through the combined effort of all members, into a galaxy-spanning empire, even though the members never met each other personally, and all of the species colonized other planets.
Though they were prepared to face an alien invasion, the Empire didn't think about an invasion from other posthumans, and so the Killer Folk, along with all of their cousins, were quickly wiped out by the Gravital as part of their interstellar conquest.
- All Tomorrows, by C. M. Koseman (2008)