Mazanderani (مازندرانی) or Tabari (طبری) is an Iranian language of the Northwestern branch, spoken mainly in Iran's Mazandaran, Tehran and Golestan provinces. As a member of the Northwestern branch (the northern branch of Western Iranian), etymologically speaking it is rather closely related to Gilaki, and more distantly related to Persian, which belongs to the Southwestern branch. Mazandarani is closely related to Gilaki and the two dialects have similar vocabularies. The Gilaki and Mazandarani languages (but not other Iranian languages) share certain typological features with Caucasian languages, reflecting the history, ethnic identity, and close relatedness to the Caucasus region and Caucasian peoples of the Mazandarani people and Gilaki people.