We know that the pits and tunnels beneath Tsotha-lanti's castle in The Scarlet Citadel were not dug by Tsotha himself; they were found three thousand years earlier by the then king of Koth, and quickly sealed up following some harrowing incident in them involving the king and his vizier. Iit was not until much later that Tsotha reopened them, explored them and began using them to dump the failed results of his sorceries. But this raises a few questions: Who did dig the pits, and what could already have been in them when Tsotha arrived?
Good question! You know, when you start thinking about it, you realise what a rich world REH built as backdrop for his yarns. Different in approach from Tolkein perhaps, but full of depth nonetheless - and a rich source of ideas for off-shoot tales. I'm surprised there aren't more Hyobrian Age tales, or is that due to copyright issues?
"All I wanted was a sharp sword and a straight path to my enemies"