I guess you could consider that the following "races", come from Old earth: (yes I too believe in Ethnic grouping as we are all one race)
Viking = Norse Culture (Scandinavia as a whole, not specific like Norwegian, Swedish, etc)
Pict = Pictish (The Irish/Scottish culture in the Bronze age)
Kelt = Celts (Iron Age Ireland, England and most of Northern/Western Europe, This includes Gaul (primarily Germanic) cultures)
Esquimaux = Eskimo peoples (Aleut, Inuit, and Yupik peoples)
Beyond those, the others are more fantasy and considered and. may in some cases be considered more of a "Race" due to their specific evolutionary body changes.
I've personally opened up Hyperborea to other cultures in my games, as one of my characters (NPC) has a mother that came through a portal from Old earth to Hyperborea and she was a Nubian Huntress, fell in with a Viking Ranger and had my NPC, Sven Svensson, a Black Skinned Viking that bridges between the Nubian and Norse cultures via his parents. I'm open for other cultures to come in also, I could see a portal opening for the Mongols, or other eastern/Asiatic cultures to find a way into Hyperborea. Maybe some South American/Native American cultures as well.
In another post, someone was looking at Barsoom and the Writings of Edgar Rice Boroughs and incorporating Mars and the cultures on it into Hyperborea, and I'd say go for it (Though I'd stay away from PCs as Green Martians, leaving PC with the standard "races" only). There are always other worlds to explore that are already in the Hyperborean universe, Saturn, The Moons, Other planetary bodies, etc. Remember, there are lost technologies of the Atlanteans waiting to be discovered!
Remember in all things, You are the GM, its YOUR world to create...