What is "titurel"

Titurel is a fragmentary Middle High German romance written by Wolfram von Eschenbach after 1217. The fragments which survive indicate that the story would have served as a prequel to Wolfram's earlier work, Parzival, expanding on the stories of characters from that work and on the theme of the Holy Grail. Titurel was continued by a later poet named Albrecht, who tied the story together in a work generally known as Jüngere Titurel ("Younger Titurel").