The Vatican library and four Japanese historical institutes have agreed to inventory, catalogue and digitize 10,000 documents from a lost Japanese archive detailing the crackdown on Christians in Japan in the 17th-19th centuries.
Monsignor Cesare Pasini, head of the Vatican's Apostolic Library, said the so-called Marega Papers represent the largest known civic archive of its kind.
An Italian missionary priest took the 22 bundles of documents out of Japan in the 1940s and brought them to Rome.
They sat in the Vatican library's storage depository for decades until a Vatican researcher who could read the characters realized their importance in 2010.
The six-year agreement signed Tuesday to inventory the documents and prepare them for study involves the National Institute of Japanese Literature and National Museum of Japanese History, among others.