The Cataclysm

The Cataclysm was a global event of great magnitude, during which virtually all knowledge across every medium and memories have been wiped from existance. The cataclysm also marked year 0 for the calender of those who survived with no memories beyond the event.
Through archeologic expeditions, only a handfull of records and archival knowledge sites have been discovered to remain intact:

The Touchstone sites, located on the continent of Namrax.
The Gnome archives, located on the continent of Cambia.
The reference to "The war in heaven", located in underground ruins in Oshia Nura.