While each Church present in Jerusalem has been studied individually, no analysis of the interactions between the various Churches, nor with the sovereign powers, has yet been carried out. This shortcoming in a well-established field of research can partly be explained by the wide range of written languages involved. Yet the academic compartmentalization of Eastern Christian and Islamic studies may have been the major factor. The ERC project ChrIs-cross will address this issue through a Connected History approach and a re-evaluation of Hodgson’s concept of the ‘Islamicate world.’ The unpublished archives of the Christian institutions of Jerusalem, which consist exclusively of Islamic legal documents, make it possible to study the ways in which non-Muslims were integrated into the Islamic(ate) world. Among these, the archives of the Armenian Patriarchate are particularly rich in information, not only on the Armenian communities, but also on other Miaphysite communities, especially the Ethiopians and the Copts, making it possible to reconstruct the networks that linked them in the wider context of Ayyubid and Mamluk societies.