The Golden Bull of Rimini was a document issued by Emperor Frederick II of the Holy Roman Empire on behalf of the Teutonic Knights. It ceded land to them which didn't belong to Frederick's Empire in the first place in return for the conquest of the same land and the conversion of its pagan population to Christianity.
Hohenstaufen Frederick II, Emperor of the Holy Roman Empire and King of Sicily and Jerusalem, was and still is regarded as a medieval thinker and philosopher breaking a lance for enlightenment and tolerance. As a proof thereof, his friendship with Muslim leaders is cited most often. The question is, is there any proof of this claimed friendship?