Clark first encountered Robert E. Howard's fantasies of Kull, Conan and Solomon Kane in the magazine "Weird Tales". He became an avid fan, and together with Miller he worked out an outline of Conan's career and a map of the world in Howard's invented Hyborian Age in early 1936 from the then-published stories. Miller sent this material to Howard, whose reply confirmed and corrected their findings. Their map became the basis of those that later appeared in the book editions of the Conan stories. Their revised outline, "A Probable Outline of Conan's Career" was published in the fanzine "The Hyborian Age" in 1938.