According to Final Fantasy IX Ultimania, Madain Sari is located where the pulse of the planet Gaia runs its most focused, and the people of Madain Sari studied the workings of nature and use of summoning magic. From their discoveries, they theorized that the eidolons are Gaia's guardians manifested from the collected belief in myths and legends accumulated within the planet's crystal. The Eidolon Wall, with the many engravings of eidolons, still survives to this day.