Semnan (Persian:, ; is the capital city of Semnan Province, situated on the alluvial fan of the Golrudbar creek in north central Iran, 216 km east of Tehran and 640 km west of Mashhad. With a population of 185,129 people, Semnan is the most populated city in Semnan Province and serves as the capital of it. The city is also the hub of the Semnani language, a sub-branch of the Caspian languages spoken to the north, and home to the Semnani ethnic group.