Annuvin

Annuvin is the Land of Death in the Chronicles Prydain universe, and also the neighbouring rival of the said main setting of the series. A massive landmass controlled by dark forces, including Arawn and it's champion the Horned King, Annuvin appears in the villains tournament, displayed by the Horned King's citadel (from the Disney's adaptation The Black Cauldron), to represent it's existence.