"It was so long ago and far away
A nation of barbarian tribes situated north of Aquilonia and separated from it by a narrow strip of the Bossonian Marches and Gunderland. The Pictish Wilderness lay to the west of Cimmeria. The high Eiglophian Mountains walled off the country from Vanaheim and Asgard on the north.
Cimmeria, birthplace of Conan, was an unremittingly somber land, "all of hills, darkly wooded, under skies nearly always gray, with winds moaning drearily down the valleys". The people were the direct descendants of vanished Atlanteans. They were tall and powerful, with dark hair and blue or gray eyes. Cimmerian tribes existed contemporaneously with Atlantis, intermarrying with Atlantean colonists on the Thurian continent prior to the Cataclysm.
Cimmerians of Conan's time were apparently still in a hunting and gathering culture, living in villages deep in the humid forests. The people used iron weapons and had borrowed other elements from the higher cultures to the south. The Cimmerian's chief god was Crom, who took little interest in human affairs.
Conan was a maverick Cimmerian, one of the few to venture out of the sopping woodlands. The Saga mentions no other Cimmerians living among the advanced nations.
Five hundred years after the Age of Conan, the Cimmerians were still ensconced in their ancient homeland. Hyrkanian invaders exploded into other Hyborian kingdoms; but their thrust fizzled out amid the ferociously defended Cimmerian hills. Only the great Nordheimr surge in advance of the glaciers finally displaced the black-haired barbarians. Many ousted Cimmerians then moved eastward, all the way to the southwestern shore of the Vilayet.
References: Hyborian Age I-II, Phoenix on the Sword, Conan the Valorous, et al.