Political position of Susa and the reasons for its economic-political fall in Sasanian era

Because of being located in a geographical position, some cities had special and significant importance in Iran history, Susa is one of them. This city has had great position due to its historical precedence in Elam and Achaemenid era and was regarded as one of the key places in the history of Iran. Susa had significant commercial-political position in Sasanian era because of being located in the way of the Silk road, however, most of the evidences are indicative of its eco-political fall in Sasanian era. Thus using historical evidences and documents, archeological findings and historical method and also relying on the references of that era, this paper attempts to investigate the position and significance of the Susa and the reasons of its fall in Sasanian era. First the geographical position of Susa is mentioned then with regard to its geographical position the reasons of its fall in Sasanian era are discussed.