نوع مقاله : مقاله پژوهشی
نویسنده
استادیار پژوهشکدۀ باستان شناسی، پژوهشگاه میراث فرهنگی و گردشگری، تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
Trade caravans, military forces, diplomatic missions, kings and their entourage, state couriers, Shiite pilgrims and hajis have inevitably crossed over the Bisotun bridge throughout history. High traffic and damage caused by natural hazards have invariably persuaded governments to invest founds in reconstruction, repair and maintenance of the bridge. Bisotun bridge is built across the Dinavar Ab River oriented on an east-west axis. It is located on the eastern outskirt of the present-day town of Bisotun, on the ‘Great Khorasan Road’. The bridge is 145 m long consisting of six spans. The main architectural components of the bridge are foundation, abutments, stone piers, cutwaters, buttresses, arches, spans, parapets, and passageway. Piers are built with well-dressed stone blocks in different sizes, while the core of the piers are packed with heaps of rubble stone embedded in generous quantities of lime mortar. Walls, buttresses, and arches are built with bricks in various sizes and colors. Prior to the archaeological excavations conducted by the present author in 2001, the Bisotun bridge was rashly designated as Safavid in the literature. However, the results of our excavations and architectural studies have revealed that this bridge was constructed, reconstructed, and restored in eight different stages. The identification of the construction phasing of the bridge is chiefly based on archaeological evidence, architectural comparative studies, type of building materials, and Thermoluminescence dating (TL). The results of our investigations have shown that the construction of the bridge substructure was initiated in the late Sasanian period, but the program was terminated abruptly, as is the case with other Sasanian projects in Bisotun. Subsequently, Ḥasanwayhids, a local Kurdish dynasty in western Iran, completed the construction of the bridge. It is evident that various parts of the bridge underwent extensive repairs or reconstructions over the subsequent periods.
Introduction
Bisotun bridge is built across the Dinavar Ab River oriented on an east-west axis. It is located on the eastern outskirt of the present-day town of Bisotun, on the ‘Great Khorasan Road’. Among the locals, this bridge is also known as Pol-e Kohneh, Pol-e Shah Abbasi, Pol-e Safavi, Pol-e Naderabad, and Pol-e Dinavar Ab.
Since the 18th century, the Bisotun bridge has been repeatedly visited but only occasionally described by travelers and scholars. Their descriptions do not contain any significant information about architectural characteristics of this remarkable bridge and its importance in the transport road network of the region. Prior to our archaeological excavations in 2001, all scholars who had written about the Bisotun bridge believed that it had only five spans and was built during the Safavid period (Kleiss 1990: 277-279; 1996a: 243; Luschey 2013: 299; Golzari, nd: 402; Azarang 1375: 204; Mokhlesi 1379: 66, 370). Their proposed dating is based on the proximity of the bridge to a caravanserai from the Safavid period.
This article aims to provide, for the first time, an accurate description of the architectural characteristics, construction phasing, and chronology of various sections of the bridge based on the results of two seasons of archaeological excavations conducted under the direction of this author in 2001 and 2002.
The Bridge and the Problem of Dating
The archaeological evidence, architectural comparative studies, type of building materials, and Thermoluminescence dating (TL) have revealed that this bridge was constructed, reconstructed, and restored in eight different stages. The construction of the bridge substructure was initiated in the late Sasanian period, possibly during the reign of Khosrow II (590-628 A.D) but the program was terminated abruptly, as is the case with other Sasanian projects in Bisotun. Subsequently, Hasanwayhids, a local Kurdish dynasty in western Iran, completed the construction of the bridge. This date is confirmed by the results of TL dating on two brick samples collected from the western part of the arch of opening no. 3 and the first circular buttress on the northwest part of the bridge. The first brick sample gave a reading of 402±60 A.H (1038±60 years ago) and the second sample provided a reading of 470±69 A.H (970±69 years ago).
The arch of opining no. 6 was rebuilt in Saljuq period. This date is corroborated with the result of the TL dating on a brick sample from the arch which gave a reading of 462±57 A.H (937±57 years ago). During the Ilkhanid period, a platform was built, with rubble stone, upon pier no. 7 of the bridge. The proposed date is supported by the presence of a reasonable number of polychrome sgraffiato and a copper coin from the time of Sultan Abu Saeed (716-736 A.H).
The northern and southern facades of the bridge were destroyed at some point between the Ilkhanid and Safavid periods, and subsequently, rebuilt in the Safavid period. Furthermore, the triangular buttresses were added to the facades. Openings nos. 1 & 2 were also deliberately filled with reused construction material. We collected 2 brick samples for thermoluminescence (TL) dating from the first triangular buttress on the southeast part of the bridge and the facade near opening no. 3. The first brick sample gave a reading of 1084±21A.H (356±21 years ago) and the second sample provided a reading of 1140±21 A.H (300±21 years ago). TL dating revealed that the samples could be attributed to the Safavid period.
During the Qajar period, part of the northern facade of the bridge was reconstructed. The TL dating on a brick sample from the northern façade of the bridge, close to the transverse arch of opening no. 3, gave a reading of 1228±16 A.H (212±16 years ago). The timeframe of the production of the brick (1244-1212 A.H) coincides with the reign of Fath Ali Shah Qajar (1250-1212 A.H). The proposed date roughly correlates with the date mentioned by Mahjoub Shirazi, a well-known poet from the Qajar period. In his poem, Mahjoub Shirazi refers to the reconstruction of the bridge that took place during the time of Mohammad Shah Qajar and by the order of Manouchehr Khan Motamed Al-Dawlah in the years 1253 to 1255 A.H.
In the first Pahlavi period, the fifth opening of the bridge was rebuilt, and the whole surface of the bridge was covered with plaster (mixture of sand and lime).
Conclusion
Bisotun lies on the very famous High Road, which connected the great cities of the Iranian plateau to the major economic and political centers of power on the Mesopotamian lowland throughout history. For millennia, this road has played a significant role in the political, military, economic, commercial, cultural, identity, religious conflicts and interactions of a part of the Eastern world. It was through this road that Islam spread from west to east or the Mongols conquered lots of territories from east to west and brought devastation to Iran and beyond. Trade caravans, military forces, diplomatic missions, kings and their entourage, state couriers, Shiite pilgrims and hajis have inevitably crossed over the Bisotun bridge throughout history. High traffic and damage caused by natural hazards have invariably persuaded governments to invest founds in reconstruction, repair and maintenance of the bridge. The construction of the bridge substructure was initiated in the late Sasanian period, but the program was terminated abruptly. Subsequently, Hasanwayhids, the Kurdish Barzikani tribe in western Iran, completed the construction of the bridge. The bridge underwent extensive repairs or reconstructions over the subsequent periods, i.e., Saljuq, Ilkhanid, Safavid, Qajar and Pahlavi periods.
کلیدواژهها [English]
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