The Celestial Mountain was the lair of the red dragon Rhodrolytharnestrix, the most powerful of the dragon tyrants of Abeir. To kill Rhodrolytharnestrix, the dragonborn rebels Iskara, Shurideh, Reshvemi, and Thuchir went to the interior of the volcano during the Battle of the Crippled Mountain, and using a powerful artifact known as the Eye of Blazing Rorn, triggered a powerful eruption that destroyed the mountain. Since then, the mountain became known as the Crippled Mountain.
The ash from the eruption fell for forty days, and the dragonborn began to call themselves the "vayemniri" (Ash-Marked Ones, in draconic), so that they would always remember the way they gained their freedom. Likewise, Clan Verthisathurgiesh, one of the most powerful clans of Tymanther, was named after the Crippled Mountain.