Alamut-e Gharbi District (), formerly Rudbar-e Shahrestan District, is in Qazvin County, Qazvin province, Iran. Its capital is the city of Razmian.
At the 2006 National Census, its population was 16,255 in 4,667 households. The following census in 2011 counted 15,056 people in 4,953 households. At the latest census in 2016, the district had 20,896 inhabitants in 7,272 households.
According to some sources, the majority of people in northern Qazvin (Alamut) are Tats who speak a dialect of the Tati language. However, other sources claim that the majority of people in Alamut are Mazanderani or Gilaks who speak a dialect of the Mazanderani language or Gilaki language.
According to some linguists, the term ‘Tati’ was used by Turkic speakers to refer to non-turkic speakers. This could explain why some sources claim the people of Alamut are Tats, while others claim they are Mazanderanies or Gilaks. Likely, the ‘Tats’ of Alamut are Mazanderani or Gilak speakers who have been labeled as Tats as historically they were considered Mazanderani or Gilaks.