They were us before us. Humans, before humans. They managed to acheive a quasi-medieval level of technology when our own ancestors were still banging rocks together. They flourished for hundreds of thousands of years. Then, for reasons unknown, they vanished. We are what evolved to take their place.
Homo sapiens borealis. These are more-or-less the "humans" of the story, although they're distinct from anatomically modern Homo sapiens sapiens. It is likely the Boreans or very recent ancestors thereof who were the ultimate progenitors of the Fairish races.
Evolution
The Boreans likely arose when a Baltic subspecies of Homo erectus, known as H. erectus borealis, some of which had migrated south into central Europe during the Gunz glaciation, interbred with Homo (sapiens) antecessor or early Homo (sapiens) rhodesiensis.
Sexual Dimorphism
Sexual dimorphism among the ancient Boreans was more pronounced than in modern H. sapiens. Male craniodental morphology tended to be more robust or "ape-like" than in modern H. sapiens, while female craniodental morphology tended on average to be more neotenous.
Borean males were, on average, about half a Borean foot (6.3 imperial inches or 16.1 centimeters) taller than Borean females. Males also tended to have proportionately longer arms and larger hands, whereas females had proportionately longer legs. Male Boreans tended to have proportionately short legs, while Borean females tended to have proportionately short arms. Borean males were "barrel-chested", with a rib cage much larger in circumferance than their hips; female Boreans display the inverse proportion, with a rib cage much narrower than the circumferance of the hips.
Height & Sex
Unusually tall Borean males could be a Borean cubit (about 48 cm) taller, or perhaps even more, than unusually petite Borean females.
Unusually tall Borean females could be half a Borean foot (about 16 cm) taller than unusually short Borean males.
Skin Colors & Patterns
Boreans had a similar range in skin tones to that found in modern humans. Whereas modern _Homo sapiens_ has mainly two color patters, plain and freckled, the ancient Boreans had a third, characterized by "blews", or patches of skin where the collagen structures cause light to refract blue, not unlike various other primates, notably the Mandrill or the Golden Snub-Nose monkey.
Types of Boreans
Cisalpine Boreans Also called Meridians or Cisalpinians. These are the peoples most responsible for what we know as Borean civilization.
High Boreans A variety of Cisalpine Borean. Descendants of the first Borean kings who took wives among the Elves.
Wild Boreans Boreans who live in the wilds and regularly mix with cavefolk, Aldelves, and in the north, Rime Boreans.
Rime Boreans Also called Hyperboreans or Transalpinians. These Boreans include the tundra nomads of the north who mix with cavefolk and wildmen.
Sea Boreans Also called Selkies. Shamanic people who inhabit islands and artificial floats throughout the Mediterreanean.