The Forgeries of Lorch, also known as Lorch Forgeries, is a collection of forged papal bulls completed in the second half of the 10th century.
Background
Most specialists agree that the collection of documents, known as the Forgeries of Lorch, was completed for Piligrim, who was made Bishop of Passau in 971. After he came into conflict with Frederick I, Archbishop of Salzburg for the ecclesiastic jurisdiction in Pannonia, Piligrim forged papal bulls. The earliest of the bulls was attributed to the 4th-century Pope Symmachus.
Piligrim believed that Lauriacum (now Lorch in Enns in Austria) was the metropolitan see of the Diocese of Pannonia in the Roman Empire. He also thought that the see had been moved from Lauriacum to Passau.
References
Forgeries of Lorch Wikipedia(Text) CC BY-SA