The research project “MONACORALE – History and Archaeology of Monasteries and Ecclesiastical sites in the Eastern Adriatic (4th-12th c.)”, is born from the collaboration of French, Croatian and Italian researchers working on archives, texts and ecclesial, and notably monastic sites of the Istrian and Dalmatian Adriatic coast between the 4th and the 12th century. It aims to constitute a reasoned corpus of these sites synthesizing all available sources and to study a "workshop area" (island of Cres, Croatia) including several major sites. Through a resolutely multidisciplinary approach combining the sources of archeology, history, history of art, literature, epigraphy, paleo-environmental study and landscape archeology, the objective will be to study : 1. the topographical aspects and the historical conditions of their foundation (relations with the natural environment, human context, reuse of ancient sites, etc.) ; 2. their territorial and social organization in the eastern Adriatic context (expansion of Benedictine monasticism and Romanesque architecture, recruitment and mobility of monks, cultural exchanges with Italy, etc.) ; 3. their functions in spreading reformist ideas and, more broadly, pontifical authority in a period of confrontation between the powers present in the Adriatic (Franks, Byzantines, Normans, Venetians, Slavs).