Tabaristani

Tabaristani gathers together the Northwestern Iranian vernaculars of the southern Caspian shore and the Semnan highlands: the Caspian languages, chiefly Gilaki and Mazanderani, also called Tabari, and the Semnani group. The name comes from Tabaristan, the medieval term for the mountain kingdom of Mazandaran, known in antiquity as Tapuria.

In the 900s the geographer al-Muqaddasi noted the distinctive speech of Tabaristan. Under local rulers after the Arab invasion, Mazanderani carried a written literature from the 900s to the 1400s, including the mirror-for-princes work Marzban Nameh and the verse of Amir Pazevari.

These tongues keep archaic Median and Parthian features and share structures with South Caucasian languages. Their literary and administrative use faded after Mazandaran entered the royal administration in the early 1600s, leaving Persian as the language of writing.