Abstract According to Islamic geographical texts, the route that passed along the southern bank of the Gamasiab River on the current Bisotun–Sahneh plain, connecting Kermanshah (Qarmisin) and Bisotun (Behistun) to Madharan, Kangavar (Qasr al-Lusus), and Nahavand, was very significant during the early Islamic centuries. However, based on archaeological evidence, it seems that a major part of this importance was attributed to the construction projects of the Sassanids, especially the later kings of the Sassanian Dynasty, such as Khosrow II, who focused on developing the current Kermanshah province, especially the Kermanshah–Bisotun region, and built extensive constructions including communication roads, bridges, palaces, and magnificent mansions along the southern bank of the Gamasiab River. The present research specifically and comprehensively investigates, for the first time, the southern route of the Gamasiab River in the southern part of the Bisotun–Sahneh plain and localises seven historical toponyms along this route. This research is mainly based on the analysis of Islamic geographical texts, especially those from the ninth and tenth centuries. Additionally, archaeological evidence such as the remains of old bridges, buildings, and sites, as well as the topographical and geographical features of the region, have been taken into consideration.
Iraj Rezaei (Wed,) studied this question.