Undeath

No one knows where the many undead came from, or why. 
Some say they came through a rift from another plane, just like the fey, dragons, and devils before them.
In some stories, Mother Ausra was given her divine powers in order to fight the imminent arrival of the undead. In others, Ausra’s new powers create the first undead by draining the energy of the living.
It is known that the undead first appear in the legends of the ausrani — yesreni legends don’t mention them at all.
The oldest dragons or treants may remember the truth.