It is generally acknowledged among scholars in the field of Late Antiquity that relations between the Roman and Iranian Empires reached its climax in the early fifth century. Countless sources report a variety of co-operative events depicting positive dealings between the Iranian shah Yazdgird and the Roman emperors Arcadius and Theodosius II. On the other hand, there exist just as many accounts that Yazdgird persecuted the Christians of his realm towards the end of his life. We are thus left with opposing narratives about the Iranian monarch, and no clarification about what truly transpired. This thesis seeks to clarify the ambiguities surrounding Yazdgird‟s reign. In order to achieve this goal, the events and circumstances that led to the apogee of Roman-Iranian relations is first retraced. An examination of potential sources of tension follows this, with the thesis culminating in the final chapter directly engaging the question of whether Yazdgird persecuted the Christians of his realm or not. The focus of this study is not solely to answer the question outlined above, but also to analyze and revise the entire topic utilizing a more holistic approach. Recent scholarship on East Syrian Christianity and the Sasanian Empire aided in providing alternative perspectives to the traditionally unilateral Roman views of the outlined issues. These different viewpoints in turn helped shape new interpretations and conclusions concerning the apogee and decline of RomanoIranian relations in the early fifth century.