On page 81, Wolfram mentions “Kancor, and Thèbit, and Trebuchet“.
Thèbit is most probably Thabet Ben Korka, a famous Arabic physician, mathematician, and philosopher of the ninth century. Kancor is probably Kenkeh, an astronomer and physician of the same period.
Source
Parzival | Wolfram von Eschenbach, 1200–1210