An Examination of the Significance of Hydraulic Structures in the Sassanid Āsōristān and Their Connection to the Arab Conquest (590-651 AD)

The Sasanian emperors heavily relied on a steady stream of financial resources to effectively govern their vast overseas territories. One of the ways they achieved this was through the construction of hydraulic structures and the promotion of agricultural development. The region of Āsōristān, situated along the Tigris and Euphrates rivers, proved to be a strategic area for the Sasanian expansionist plans. The rulers of the Sasanian Empire referred to the southern part of Āsōristān as the heart of Iranshahr due to its fertile land and high population density. The state’s abundant arable lands, coupled with the implementation of effective irrigation policies by the Sasanian rulers, led to a prosperous agricultural sector in the region. The establishment of new cities and the improvement of hydraulic structures further contributed to the growth of the population and the development of arable land, consequently resulting in increased tax revenues for the state. However, man-made water structures necessitated specialized oversight and upkeep by labor. Despite significant investments by the government in irrigation projects, these structures tended to deteriorate without proper maintenance, and the absence of enough workers due to chronic wars and failure to rebuild led to the development of the wetlands. The economic prosperity and military might of the Sasanian Empire were interconnected, and the collapse of either could spell doom for the imperial system. This study aims to explore the relationship between the Āsōristān hydraulic structures and the Arab conquest using library resources and a descriptive-analytical approach. According to historical records, the research findings indicate that following the rule of Khosrow Parviz, the participation of Iranians in internal conflicts, coupled with the neglect and failure to repair hydraulic systems, led to the expansion of wetlands in Āsōristān and the devastation of crucial agricultural areas due to massive floods. The Āsōristān region, which used to generate the highest tax revenue for the Sasanian Empire, experienced a decline. The economic prosperity of the empire was closely tied to its military might, which contributed to the downfall of one aspect that was interconnected with the collapse of another aspect.