The eastern heights of Sarāb-i Bīd-i Surkh, located about 15 kilometers west of

Kangavar in the west of Iran, served as a significant historical passage in the central Zagros region, along the route connecting the Iranian Plateau to Mesopotamia throughout history. Today, the Tehran-Hamadan-Kermanshah-Baghdad road crosses one of the passes of these heights, known

locally as the "Gardaneh-i Bīd-i Surkh". However, numerous historical and archaeological pieces of evidence suggest that other routes were also utilized in the past to cross the mentioned heights.

The present study, for the first time, explores all the previous routes that have crossed the eastern heights of Sarāb-i Bīd-i Surkh based on historical texts and archaeological evidence. The research aims to investigate communication routes between the Kangavar and Sahneh Plains over different periods and reconstruct the location and characteristics of each route. Accordingly, four different routes have been identified including: 1. the Bīd-i Surkh Pass route, 2. the northern route (Qazvīneh), 3. the Sarāb-i Mārān route (ancient Mādharān route), and 4. the Duāb route. In this research, the characteristics of each route have been examined separately. The existing archaeological evidence, including the remains of the old paved road, the distribution of ancient

sites around the routes, as well as the remains of bridges, and related security facilities such as castles, observation posts, and guardhouses left on the heights of the region, indicate the existence of these routes in the past and the importance of the eastern heights of Sarāb-i Bīd-i Surkh as a strategic passageway in different historical periods. Accordingly, it seems that sometimes in a specific historical period more than one route was used to cross the eastern heights of Bīd-i Surkh, and the use of each route depended on various factors such as the season, road safety, type of caravan (light or heavy), road quality, etc.