Gonna place my claim between the red Empire, and The Narrator´s land! Thinking about a heretic kingdom, that was driven out of Justinian Imperium, and who´s great values have been perverted, until it turned into a slaving ariostracy, rather then a enlightened Republic! 

Alternatively, i would go for spider Riding Nomads, who mostly dwell in the tunnels under the Claws, and now came out to take on the land above!