摘要：The paper deals with the key aspects of the development of the diplomatic relations of the Late Roman Empire and the Sasanian Iran during the reign of Justinian I (527-565). It is noted that despite the significant political changes that took place in Europe after the fall of Roman imperial power in the West, the Eastern Roman Empire remained the leading power in the region. The Sasanian state was the only international partner equal to its status. The long-standing relations between the two leading powers contributed to the establishment and development of international legal norms and diplomatic rituals. From this point of view, an important period in the development of Roman-Iranian relations was the reign of Emperor Justinian I (527-565). Roman-Iranian relations and late-Roman diplomacy repeatedly became the objects of study, both of classic specialists in antiquity and Byzantine Empire (E. Gibbon, J. Kulakovskyi, F. Uspenskyi, and others), and modern scholars (W. Treadgold, D.Y. Mishyn, and others). However, certain important aspects of Justinian I's diplomacy remained unstudied. The goal of the paper is to study the late Roman diplomacy of Justinian period in relations with Sasanian state in dynamic development. Particular attention is paid to the circumstances of the establishing of «Eternal Peace» (532) and «Fifty-Year Peace» (562), as well as Late Roman subsidiary diplomacy. During the reign of Justinian I (527-565), late-Roman diplomacy in relations with Iran went through a controversial phase of development. By the 520s, the Empire had developed the long-term traditions of relations with the mighty powers of the East. Roman and Iran rulers fought for domination in the Middle East, and the efforts of diplomats of both sides played a great role in that fight. There was some parity between the Roman Empire and Iran. In diplomatic correspondence, it was emphasized by the «brotherhood» relations established between the emperors and the «kings of kings» of Sassanid dynasty. Other states and peoples of the region were more likely to act as satellites of one of the empires. Part of the practice of bilateral relations was the monetary subsidies paid by the Romans to Iran for the Caucasus mountain passes protection. Those subsidies were often interpreted as a ransom paid for peacekeeping. However, they objectively gave the Romans freedom of action at other borders and not to keep large military contingents in the East. Such a situation was successfully used by Justinian I for the implementation of the Renovatio imperii in the West after the establishing of «Eternal Peace» in 532. Although the military conflict between the Romans and Iran repeatedly took place in the 540s – 550s, the activities of Justinian I’s diplomats became not less decisive factor in the containment of Khosrow I than the military force. The Peace Treaty of 562, which settled the relations between the Roman Empire and Iran, was the result of the policy of Emperor Justinian I in the Middle East. Roman diplomacy got the opportunity to hold the position in the region while the main armed forces of the Romans operated in the West. Iran succeeded in receiving monetary subsidies that confirmed the Romans' willingness to maintain long-term peace on their eastern border.
