Position of Caucasus and Its Border Ramparts in Sasanid Interactions with Roman Empire

Border closure and establishing border ramparts have a long precedence in Iranian defense policy. As an important geographical and strategic region, Caucasus has always had a significant place in Iranian dynastie's interactions with their neighbors in the northwest regions. The ramparts of this region have had a main role in preserving and fostering a part of political, economic, social and religious interests and greed of Sasanid Empire and its relations with the Roman Empire. This article seeks to respond this question: What factors did cause that Caucasus and its border ramparts play an important role in the interactions of these two great powers? The results indicate that Sasanid Empire closed borders, established border ramparts, castles and border towns in order to prevent different aggressive tribes trespassing Iranian borders in the Caucasus region. The role of these border ramparts was also important in Sasanid foreign policy towards confrontation with these aggressive tribes and preventing them from entering Roman Empire territory for which Sasanids received financial costs from Roman Empire.