For any historian, the lack of documentation on a certain subject, a certain reign, a certain institution, always gives the feeling that something remains incomplete, untold, without history. This is a transversal feeling, whether we are talking about medieval, modern, or contemporary historians. Unfortunately, it is common for us to encounter these gaps due to many different, accumulated vicissitudes. The main objective of this project is to try to remedy the lack of documents (especially medieval documents) from two monastic institutions - the Monastery of San Salvador de Grijó and the Monastery of Rendufe - by reconstructing their archives.