One of the seven great wyrms, Bahamut was slain while fighting against the Allagan invasion of Meracydia. His brood-sister, Tiamat, led the surviving dragons in a summoning ritual, and their prayers resurrected the dreadwyrm as an avenging primal. A terrible incarnation of wrath and fury, Bahamut descended upon the heart of the conflict and incinerated the northern invaders with ruinous flames. He was eventually undone by the might of the anti-primal weapon, Omega, and his undying rage was sealed within the core of Dalamud. For millennia, the shackled entity's command over flare and fire was employed to harness and store the energy of the sun.
Then came the fateful end of the Sixth Astral Era. By enthralling the mind of the Garlean legatus, Nael van Darnus, Bahamut was able to manipulate the direction of the Meteor project, and thus free himself in the skies above Carteneau. Released from the red moon after five thousand years of imprisonment, the furnace of the dreadwyrm's vengeance immolated the lands of Eorzea, and ushered in the aether-warping devastation of the Seventh Umbral Calamity.