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.
Johann Sebastian Bach's Christmas Oratorio lay in musical archives for over 100 years. They were rediscovered around 1850. And music historians were amazed and dismayed: Bach had composed and used important parts of it before and plagiarized earlier compositions into the work. The originals, however, had very different texts, and these were not at all for Christmas or any liturgical use.