In a couple of Lovecraft's stories, he references The Cruel Empire of Tsan-Chan which is to come on Earth in the year 5,000. Specifically, the Empire is mentioned in The Shadow Out of Time, and Beyond the Wall of Sleep.
In 2010, Chaosium published a short book detailing what they think it might be like.(It's hard to find now.)
I just think it would be a cool place for a race of humans on Hyperborea to hail from.
Brian