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In El Phildin, a battle was fought with god against god between Bardus, the god of light and Octum the god of darkness. The battle ended with Bardus imprisoning Octum in the Sealed Land, and their battle left genesis myths which were worshipped for future generations.
The gods hibernated from existence and without their interference, an ancient civilization called the Blue Tribe perfected the use of Resonance Magic. No sooner, the magic centralized as the boom of magical culture, inventing the usage of teleportation gates. People began to explore from new frontiers, eventually discovering the existence of Another World.
However, the resonance of the magic also generated negative energy called the "Waves of Raual". Due to its worldwide management, the harmful frequencies emitted by the energies went out of control resulting in the ban of Resonance Magic. To prevent further cataclysm, the Blue Tribe used an instrument called the Viola Ruhm to harness the Waves of Raual to send masses of negative energy to Another World. The repressed remains were stabilized in resonance with the waves, resulting in the Gagharv World known as of the trilogy's present.
Since then, the Blue Tribe disappeared from existence and world's history, leaving behind its descendants in Weltluna.