From Halopedia, the Halo wiki
K'tamanune were a variety of human that evolved on Erde-Tyrene over the course of nine thousand years following the Librarian's relocation of survivors of the last war against the Forerunners to their race's ancestral homeworld.
K'tamanune were husky and either ocher or brown-skinned. They resided in Erde-Tyrene's northern latitudes in the days which preceded the firing of the Halo rings in 97,445 BCE. There they wandered and skirted massive grinding sheets of ice. These dwellers in glacial shadows wrapped themselves in harsh woven fiber and fur. Some humans in their day chose to build crude cities, as if struggling to require past greatness—but failed miserably. When humans imprinted with the Librarian's geas were gathered for evacuation just before the Halos' were activated, some of those living across a thick northern cloak of glaciers on Erde-Tyrene were among them.
Behind the scenes
K'tamanune have only been mentioned once, within the first book of The Forerunner Saga, Halo: Cryptum. It may be possible to identify them as neanderthals, who resided in northern Asian and European climes and are known to have been stronger than anatomically modern humans. As such, k'tamanune may also briefly appear in Halo: Primordium, as Chakas describes four human females unlike any of the other varieties he'd encountered who possessed long heads, prominent but chinless jaws, and graceful, loping gaits.
List of appearances