Golden Bull of Rimini

The Golden Bull of Rimini was a Golden Bull issued by Emperor Frederick II, at his court in Rimini in March 1226 to confirm the Teutonic Knights' possessions in Prussia. It was the first of three similar documents, followed by the Treaty of Kruschwitz (Kruschwitz) in 1230, and the papal Golden Bull of Rieti in 1234.

The Piast duke Konrad I of Masovia had waged several Prussian Crusades and particularly in 1222/23 had tried to conquer Chełmno Land (Culmer Land) east of the Vistula River from the pagan Old Prussians. Backed by his Polish cousins Leszek I the White and Henry I the Bearded, he initially was successful, but had to face a Prussian counterstrike and now feared for his Duchy of Masovia, which suffered under continuous Prussian attacks. In 1224 the duke began negotiations with the Teutonic Knights to strengthen his forces and to stabilize the situation.

Between 1211 and 1225, the Teutonic Order, led by Grand Master Herman of Salza, was present in the Burzenland region of Transylvania. Similar to Konrad of Masovia's request, the Knights had been called in by King Andrew II of Hungary to settle, stabilize and protect the eastern Hungarian frontier against the Cuman people. Yet, they were expelled after trying to establish an autonomous state on Hungarian territory, subordinate only to the authority of Pope Honorius III. This time von Salza would wait to set out for Prussia, until the Order's claimed possessions were confirmed directly by the Holy Roman Emperor.

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