Valusia is the oldest and most splendid kingdom of the Thurian Age, predating even the submergence of Atlantis. Howard presents it as a civilisation of deep ceremonial history, its outward grandeur concealing profound inner corruption.
The central horror of Valusia is that the Serpent Men — perfect mimics of human form — have infiltrated its court, nobility, and priesthood at every level. In "The Shadow Kingdom" Kull uncovers the conspiracy, yet can never be certain how many around him have been replaced.