Robert E. Howard devised the Hyborian Age as the post-Atlantean setting of his Conan stories, designed to fit in with some previous and less-well-known tales he wrote set in Atlantis. The name "Hyborian" is a contraction of the Greek concept of the land of "Hyperborea", literally "Super-North-Land". This was a mythical place far to the north that was not cold and where things did not age.

Howard's Hyborian age is a mythical time before any civilization known to anthropologists. Its setting is Europe and North Africa – with some curious geological changes that were thought up prior to the ascendancy of the geologic theory of plate tectonics, though somewhat similar to what geologists theorize. They consider that during the Ice Age, Europe was quite different. The Mediterranean Sea formerly dried out intermittently, alternating with floods over the Straits of Gibraltar. Once there was a land-bridge across the English Channel between England and the Low Countries (but not across the Irish Sea) such that the Thames once flowed into a northern extension of the Rhine. And both the Baltic Sea and the Black Sea were once fresh-water lakes, the former (renamed the Ancylus Sea, after a fresh-water clam) covering much of what is now Sweden.

On a map Howard drew detailing it, his vision of the Mediterranean Sea is also dry. The Nile, which he re-named the River Styx, takes a westward turn at right angles just beyond the Nile Delta, plowing through the mountains so as to be able to reach the Straits of Gibraltar. Although his Black Sea is also dry, his Caspian Sea, which he renames the Vilayet Sea, extends northward to reach the Arctic Ocean, so as to provide a barrier to encapsulate the settings of his stories. Not only are his Baltic Sea and English Channel dry, but most of the North Sea and a vast region to the west, easily including Ireland, are too. Meanwhile, the west coast of Africa on his map lies beneath the sea. There are also a few islands, reminiscent of the Azores, but his stories are not about naval tactics.

In this general setting, Howard placed imaginary kingdoms to which he gave names from a varied series of sources. Khitai is his China, far to the East, deriving from an ancient name; Corinthia is his name for a Greek-like civilization, a name slapped together from the name of the city of Corinth and a reminiscence of the medieval province of Carinthia. He imagines the Picts to occupy a large area to the northwest. The probable intended correspondences are listed below; notice that the correspondences are sometimes very loose, and are portrayed by ahistorical stereotypes.