An area of Mars inhabited by the Clay People. All Martians tranformed into Clay by Queen Azura are banished here. Martians fear this region as to cross its borders means certain death; nobody ever returns.
The Clay King is heard to say that anybody who spends too long in the Clay Kingdom will themselves be transformed into Clay. Dr. Hans Zarkov theorizes that this is an effect of the vapours emanating from the walls of the caves.