In 1491 DR, Rhundorth was chosen among many others to be part of a diplomatic delegation. However, at Beliard in the Dessarin Valley, they were ambushed by the Cult of the Black Earth. Rhundorth was captured and transported beyond the River Dessarin. He remained in the Black Earth's hands.
The earth cultists made him toil for the Cult under the promise of better treatment for his fellow prisoners. Eventually, some adventurers infiltrated the Fane, defeated the cultists, and saved him.