The first of the aboriginal Hyborian tribes who discovered the use of stone in building, the Hyperboreans abandoned their primitive, nomadic way of life to settle in huge walled dwellings of stone, consequently founding the very first, but most isolated, of the Hyborian kingdoms.
The citadels of Hyperborea are impressive even by Hyborian standards. They are made from mortarless stones carefully fitted together and dressed smooth to give no foothold for a climber. The walls are turreted and crenellated, fifty feet high and twenty paces thick, giving the fortresses a squat appearance. Windows and arrow-slits are set into the walls, too high to be entered, but low enough to allow effective defense. The ironwood gates are protected by iron portcullises and decorated with protective runes formed by patterns of iron nails.
The western boundary of Hyperborea with Asgard is the River of Death Ice, having its source in the Eiglophian Mountains. This stream is shallow and clogged by glacial debris. Since it's also frozen throughout the long winters, the river provides an ineffectual barrier against invading bands of Aesir. The land of Hyperborea is wild, mountainous, gloomy, and damp, with its main pass the ominously named Skull Gate.
The people are pale-skinned, extremely tall, and gaunt, with white hair and cat-green eyes. Many are as tall as seven feet. They are a superstitious people who live as shamans in wooden huts beyond the stone walls, where they spend their harsh lives by gardening the stubborn soil or herding small numbers of shaggy cattle and reindeer.
Hyperborea is ruled by the White Hand - a coven of sorcerers not unlike the Black Ring of Stygia or the Scarlet Circle of Khitai. The White Hand "Witch Masters" are the priests or priestess of Louhi, the ever-reincarnating goddess over the Hyperboreans, as well as accomplished sorcerers. Their magic focuses around the cold of their land and control over the dead. Hyperborean sorcerers are highly prized in the northern wilds, but they are little respected in Hyborian lands.
Hyperborea also hosts several bands of hardy slave raiders, who peform repeated forays into Cimmeria to fill their slave pens. According to tales, Conan was taken captive by Hyperborean slave traders early in his youth.
After the Age of Conan, Hyperborea was conquered by Hyrkanians who galloped around the frozen tundra north of the Vilayet Sea.