An Inquiry in Archaeology of Qala-i Sam in Sistan (Study of Architecture, Relative Chronology, Real Identity, and Political Status and Function)

The ancient Sistan was a vast and prosperous territory considered as one of the most important Iranian states since the ancient times. This land is extended from the north of the Indus and Arghandab Rivers to Zahedan Mountains and its main part is a wide and flat plain including Sistan and Nehbandan in the Iranian territory and Nimruz, Farah and Helmand states in the Afghan boundaries. Throughout this region, remnants of ancient cities and towns have been remained as a collection of continuous ruins, mounds and embankments that each represents different features both in terms of time and location and also function and architectural structure. One of these important sites is Qala-i Sam. This castle, located in the center of Sistan, is one of the most significant and largest sites of the historical eras in the eastern Iran that to this date, despite its great importance, no scientific studies and research have been performed on this site as it deserves and questions such as the settlement period or periods, architectural structure, real identity, and position of this site in the political and social system of its time have still remained unanswered. Accordingly, a research plan based on a comprehensive and general survey was implemented on this site. In this research plan, while studying the architectural evidence, sampling was carried out based on collecting the significant surface samples for relative chronology on the basis of typological comparison so that all the features and characteristics of this place could be identified and recorded; and finally, by comparing the material evidence with the historical sources based on a historical approach, the real identity of this site was investigated. Based on the performed typology, the surface pottery samples existing on this site were categorized into three periods. The first category includes Seleucid pottery which is analogous with the Seleucid pottery of the sites such as Susa, Charsada, Laodicea and Kangavar. The second category includes some Parthian pottery which is comparable to the Parthian pottery of the sites such as Qala-i Kulak, Kuh-e Khajeh, , Kok-e Kohzad, Tape-i Gouri, Qumis, Bistun, Qala-i Yazdgerd, Qorveh, and Kelardasht, Nush-i Jan, Bardsir, Qeshm and MahNeshan. And the third category is consisted of Sasanian pottery that can be compared with Parthian pottery of sites like Bandian, Kush, Atashkuhe, Kaferun, Ramshahrestan, Qala-i Kulak and Mahneshan. The obtained results indicate that Qala-i Sam site has been constructed during the Seleucid period and its extensive settlement continued until the early Sassanid era. It is likely that, this site has been the remains of a city known as Agriaspi mentioned in historical texts which has been the seating place of the royal families during the Seleucid and Parthian periods as the central city of Sistan. According to the performed studies, it can be argued that Qala-i Sam is remains of a historical castle-city with an enclosed space which has more than 11 hectares area with a peripheral connection extended beyond a few dozen hectares. This site with a regular and trapezoid-shape structure has a hypodam plan and the remains of the buildings and constructions existing in it imply an orderly, regular, and coordinated architecture that attests to the principles of a hypodam architecture urbanism. Most likely, this site is the remains of a Seleucid-Parthian city known as Agriaspi, mentioned in the Greek texts, that during the Seleucid eras and afterwards, during the Parthian periods, was considered as the governmental seat of the Sistan Plain and has played a central role compared to its contemporary sites; and eventually, in the early Sassanian era, this site has lost its political position due to some reasons.