Dawn Cataclysm

The Dawn Cataclysm was an attempt by the god Lathander to reshape the pantheon of deities more in his own image. It is unknown when this event occurred but Lathander failed, resulting in the destruction of several deities and "powerful outsiders".

A Historical Puzzle
The precise chronology of the Dawn Cataclysm in mortal terms is murky, and no historian of the Realms was able to date it definitively. Did it happen before or after the first of the Magisters was ordained by Mystra? Was the Dawn Cataclysm, as some claim, an event that climaxed in the Year of the Hangman's Noose, 161 DR, when the last of Tyche's chosen died in the coils of Moander? Was it the culmination, in part, of the battle between Savras and Azuth? No mortal could say for sure.

Timeline

 * -339 DR : The Fall of Netheril. The transformation of Mystryl to Mystra.
 * -255 DR : Jhaamdath falls.
 * 136 DR : Shornthal Imynster becomes Magister.
 * 171 DR : Moander is sealed away in Yûlash.
 * 261 DR : The founding of Myth Drannor.
 * 714 DR : The fall of Myth Drannor.
 * 760 DR : Rhyester writes the Sermon of the Eclipse.