Kermānshāh, formerly Bākhtarān,  city, western Iran. The city lies in the fertile valley of the Qareh Sū River and is situated on the ancient caravan route between the

Mediterranean Sea and Central Asia. It was founded in the 4th century ad by Bahrām IV of the Sāsānian dynasty.

Conquered by the Arabs in 640, the town was called Qirmasin (Qirmashin). Under Seljuq rule in the 11th century, it was the chief town of Kordestān. The Ṣafavids (ruled 1501–1736) fortified the town, and the Qājārs repulsed an attack by the Turks during Fatḥ ʿAlī Shāh’s rule (1797–1834). Occupied by the Turkish Army in 1915 during World War I, it was evacuated in 1917. The construction of a road in the 1950s over the age-old Khorāsān track added considerably to the importance of the city. It is now a fairly important industrial centre; industries include textile manufacturing, food processing, oil refining, carpet making, sugar refining, and the production of electrical equipment and tools. It is connected by road to Tabriz, Hamadan, and Qazvin and has an airport.