This volume provides an analysis of a late fifteenth century document, a hitherto unpublished narration of the life and accomplishments of Yūḥanun Bar Šay Allāh, a fifteenth-century Syriac Orthodox Patriarch. This biographical account is part of a Syriac manuscript found in Cambridge University Library, with the shelf mark DD.3.8(1) and contains, as its main subject, the Ecclesiastic History of Bar Hebraeus. It includes considerable unique historical information, shedding light on the history of the Syriac community in relation to other communities. It also supplies descriptions of events that brought important changes to the Syriac Church in Mesopotamia, Syria and Egypt.