zu'aan (roughly translated to 'the walkers') are a bipedal mammalian species that evolved on Terael over four million years ago from a more primitive primate creature. Pack oriented and communalistic, the zu'aan maturated under great enviromental stresses, eventually developing a rich culture and religion that exemplarized faith, rash bravery, and determination. For hundreds of years these traits aided the zu'aan in the conquest of their world. Despite an ice age that set back their civilization and a growing bifurcation between thsoe who embraced civilization and those who wished to retain their connection to the wilds.
As time passed, their unity became more stressed, eventually splintering along the lines of nation-states orbiting a main, centralized Empire, called the Xerea Empire. Some twenty-five decades ago, the zu'aan began experimenting with radical technologies, including viral therapy, nanolevel genetic manipulation and retroviral alteration. The goal, brought about at the orders of a government looking to create supersoldiers, resulted in the creation of a virulent virus that altered the zu'aan it affected into creatures called kin'toni. Containment on this failed when a scientist working on studying the results was bitten by a lab animal, and concealed his infection.
When he turned fully and converted the rest of the scientists in the lab to kin'toni, there was no one left to understand how to combat or cure the virus. Given the tightly linked nature of any advanced civilization, the infection spread rapidly via transit lanes, city centers and water connections. It engulfed the main aspects of zu'aan society so fast the existing governments had little chance to halt it's spread, and the central government splintered as the Empire burned. The zu'aan were far too stubborn to simply die, and many fled. Some established safe zones in areas of the world where geography and fortifications evened the odds, others fled back into the wilds.
As the years have passed, more and more zu'aan have fallen to the ranks of the kin'toni, who now outnumber them and cover the globe. A few stubborn holdouts of civilization remain, and more tribal groupings still wander the land, but for the most part the high technology and machinery of their past glory is gone, twisted wreckage rusting under the uncaring sun—or worse, in the hands of ancient kin'toni who know more about it than the zu'aan. Their fate is almost certain doom. They are slowly dying, forced to fight over the dwindling sustainable land by the deadly fingers of ice crawling down from the north, and living in constant fear of the kin'toni waiting unseen outside their open gates.
With their hospitals gone and a cultural hatred for doctors and medicine stemming from the kin'toni virus, they are ravaged by disease. The ice age that relented slightly a thousand years ago now grows stronger. With sheets of ice creeping south and north from the poles to crush all beneith endless glaciers. Despair and reckless hate lead many more into hopeless fights or suicide, and few zu'aan even live long enough to reproduce or see twenty years of age.