The archaeology and history of the Roman centres in the southeastern Anatolia has been a subject that has been generally neglected by modern scholarship. In this thesis I hope to help fill this major gap in scholarship. In general, the thesis critically examines the known history and recent archaeological identity of the Upper Tigris Basin from the reign of the emperor Septimius Severus to that of Anastasius I. It is based on a detailed analysis of the primary and secondary sources for the historical geography of the region and the results of surveys and salvage excavations that have mostly been obtained in connection with the Ilısu dam project. As such, it sheds light on current thinking and the available evidence on how the Romans considered and viewed the Tigris as an eastern borderland and in this way achieves a better understanding of the character and the nature of Roman military and diplomatic strategy on the Upper Tigris and the concomitant border region.