This article offers a contextualizing analysis of archeological, iconographical and epigraphical data discovered mostly in the late 1990s at Dayr as-Suryān in Wādī-n-Naṭrūn between Cairo and Alexandria. It highlights the historical relations between the Egyptian (Coptic) and Syrian Christian communities and the presence of Syrian monks at the monastic site in question, as well as in Cairo and in Egypt generally. The main textual evidence studied consists of epigraphical material that may be considered to be “synodical inscriptions” as they are shown to be related to the exchange of the well-established tradition of exchange of “Synodical Letters” between the patriarchs of the two non-Chalcedonian sister Churches. Four such inscriptions, dated to the 8^th, 9^th, 10^th, and 11^th centuries A.D., are compared to external evidence and more particularly to Copto-Arabic historiography. In a concluding analysis, this phenomenon is briefly studied within the larger context of contacts and exchanges between the two communities and the migration of Syrian and other Oriental Christians to Egypt.