I saw bits and pieces of it.
It appears as one of the lands in his fiction cycle, who in turn was connected with H.P. Lovecraft's concepts and was expanded by the other writers who played with the same ideas, especially Clark Ashton Smith.
From Wikipedia: "In Greek maps from the time of Alexander the Great, Hyperborea, shown variously as a peninsula or island, is located beyond France and has a greater latitudinal than longitudinal extent. Apparently Hyperborea is a combined notion of present day Britain and Norway/Sweden."