The Interment Gates

When they destroyed magic and buried the gargantua, the Great Kingdom built four gates in the territories of the four great magical races: the aarakocra, dragonborn, tritons, and yak folk. These gates were used to inter the gargantua and the Weird Made Flesh, then sealed forever using four keys called the Namzaqu.
The four races were charged with protecting the gates so that no one would ever wake the gargantua and the Weird Made Flesh; this was done because the Great Kingdom hoped to erase magic from the living memory of the mundane races, but knew that the magical races could not forget their heritage. Instead, the magical races lived in isolation from the rest of Midavel.
The Great Kingdom also created a final race to act as guardians should the chosen four ever fail; these were the genasi.
See also Magical Races