During the Mamluk period, Cairo was renowned for its book markets and the richness of its public and private libraries. Book collectors, including scholars and prominent Mamluk amirs who vied to collect the rarest items, played a vital role in preserving earlier manuscripts and in commissioning the production of copies. Thousands upon thousands of these books later enhanced Ottoman and European libraries. Over the last century, there has been renewed interest in the history of the book, libraries, book-collecting, and reading in Islam. While several studies have been published, these focus on data provided by primary sources (chronicles, biographical dictionaries, treatises, catalogues of libraries, etc.), but largely overlook information supplied by the books themselves: ownership marks, reading notes, seal impressions, and so forth. These paratextual marks are now the object of greater scrutiny, as they constitute original pieces of valuable information on the history of the books. More than ever, these marks also give us the opportunity to analyze the itineraries of these objects. The Ex(-)Libris ex Oriente (ELEO) project aims to gather together as many of these marks as possible, in order to carry out various research projects in this growing field. The goal of this lecture is to present the database, the projects linked to it, and the preliminary results the project has yielded since the database was launched in 2015.