Task: Question Generation
Input (English): The Chronicle provides a mythic tale of Oleg's death. A sorcerer prophesies that the death of the Grand Prince would be associated with a certain horse. Oleg has the horse sequestered, and it later dies. Oleg goes to visit the horse and stands over the carcass, gloating that he had outlived the threat, when a snake strikes him from among the bones, and he soon becomes ill and dies. The Chronicle reports that Prince Igor succeeded Oleg in 913, and after some brief conflicts with the Drevlians and the Pechenegs, a period of peace ensued for over twenty years.
Output (English): What was prophesised by a sorcerer involving Oleg's death?