Ancient Borea, or rather the mythological world ellucidated in The Palæoboreanica (the primary source of ancient Borean mythology) is a setting I created for The Sovereignty Cycle, with the intention of replacing the alternate history “place holder” setting I used when I began writing the first story of that series.
“The Sovereignty Cycle” is a series of novels I was writing from 2000 C.E. to 2013 C.E. (which I plan to finish now that I’ve got the files off of the crashed hard-drive I had the documents stored on). For more information, see Fiction & Worldbuilding: The Sovereignty Cycle.
Inspirations included The Epic of Gilgamesh, Homer’s Illiad & Odyssey, Hesiod’s Theogeny, the works of Aeschylus, Sophocles, Euripides, Virgil, Horace, and Ovid, Beowulf, the Poetic Edda, Snorri Sturluson’s Prose Edda, Jacobus da Varagine’s Golden Legend, Dante Alighieri’s Divine Comedy, Bram Stoker’s Dracula, James Frazer’s The Golden Bough, and Eric Rücker Eddison’s The Worm Ouroboros.
I used the false document technique a la Tolkien or Lovecraft so that I could have magic in the story and justify it as an ancient culture's mythology rather than magic being "real", but yeah, Howard was probably a bigger influence on the setting. The reason I put it so much further in the past and with a fictional hominid species came from watching a TV special about what would happen if humans suddenly disappeared; it said in 100,000 years all of our buildings would have long since been destroyed by plants and almost no traces of us would be left. So I figured if they lived more than 100,000 years ago, it's somewhat plausible that they could've evaded discovery until now, especially if most of their cities were built on coasts that are now underwater. Then I decided I wanted a temperate climate and certain fauna so I picked 500,000 to 300,000 years ago. And because H. sapiens sapiens didn't exist yet and their ancestors weren't yet capable of higher technology, I decided the "humans" in my story would actually be _Homo borealis_, a species that would eventually become extinct and whose vacant evolutionary niche we evolved to fill.