In the previous Mamodo Battle, the Mamodo who defeated the most foes was Goren of the Stone. His ultimate spell, Dioga Gorugojio, petrified the victim along with their spellbook, imprisoning them indefinitely and removing their claim to the throne in that battle. Around 40 Mamodo fell victim to this spell, and remained trapped for the next millennium. It was not until the next battle began that the Mamodo Zofis gathered them together, with the help of his associate Byonko, and freed them with his mysterious creation, The Moonlight Stone.
The first appearance of a Stone Tablet is in episode 22 (chapter 53 in the manga), when Kiyo's father shows him one that was in a museum, later revealed to be the Mamodo Demolt, connecting it with the battle due to the markings on the tablet that were similar to those in the Spellbook. Later, Kiyo finds another stone tablet, this one belonging to the Mamodo Pamoon, and experiments on it to attempt to discover what it is. This proves fruitless, and the tablet is stolen before he can make any further progress.
The Ancient Mamodo were used by Zofis in an attempt to claim the throne without having to rely on anyone else. However, this threat was identified by Dr. Riddles, who subsequently attempted to gather allies among the other Mamodo in the battle, alerting Zatch Bell and Kiyo Takamine, Tia and Megumi Ooumi, Kanchomé and Parco Folgore, Wonrei and Li-en, and Brago and Sherry Belmont, as well as helping Ponygon find his own partner, Kafk Sunbeam. With the amassed force fighting against the Ancient Mamodo, all of them ultimately had their books destroyed, and returned to the Mamodo World.