Old Azeri

Old Azeri (آذری, Āzarī; also spelled Adhari, Azeri or Azari) is the extinct Iranian language that was once spoken in the northwestern Iranian historic region of Azerbaijan (Iranian Azerbaijan) before the Turkification of the Azerbaijani people. Some linguists believe the southern Tati varieties of Iranian Azerbaijan around Takestan such as the Harzandi and Karingani dialects to be remnants of Old Azeri. Along with Tat dialects, Old Azeri is known to have strong affinities with Talysh and Zaza language and Zaza and Talysh are considered to be remnants of Old Azeri. Iranologist linguist W. B. Henning demonstrated that Harzandi has many common linguistic features with both Talysh and Zaza and positioned Harzandi between the Talysh and Zaza.

Old Azeri was the dominant Iranic language in Azerbaijan before it was replaced by Azerbaijani, which is a Turkic language.

Ahmad Kasravi, a preeminent Iranian Azeri scholar and linguist, was the first scholar who examined the Iranian language of Iran's historic Azerbaijan region. He conducted comprehensive research using Arabic, Persian, Turkish and Greek historical sources and concluded that Old Azeri was the language of this region of Iran before it adopted the Turkic language of the same name. Historical research showed that Azeris were an Iranic people before the arrival of Seljuq Turks to the region.

Old Azari was spoken in most of Azerbaijan at least up to the 17th century, with the number of speakers decreasing since the 11th century due to the Turkification of the area. According to some accounts, it may have survived for several centuries after that up to the 16th or 17th century. Today, Iranian dialects are still spoken in several linguistic enclaves within Azarbaijan. While some scholars believe that these dialects form a direct continuation of the ancient Azari languages, others have argued that they are likely to be a later import through migration from other parts of Iran, and that the original Azari dialects became extinct.

According to Vladimir Minorsky, around the 9th or 10th century:

The original sedentary population of Azarbayjan consisted of a mass of peasants and at the time of the Arab conquest was compromised under the semi-contemptuous term of Uluj ("non-Arab")—somewhat similar to the raya (*ri’aya) of the Ottoman empire. The only arms of this peaceful rustic population were slings, see Tabari, II, 1379-89. They spoke a number of dialects (Adhari, Talishi) of which even now there remains some islets surviving amidst the Turkish speaking population. It was this basic population on which Babak leaned in his revolt against the caliphate.

Clifford Edmund Bosworth says:

We need not take seriously Moqaddasī’s assertion that Azerbaijan had seventy languages, a state of affairs more correctly applicable to the Caucasus region to the north; but the basically Iranian population spoke an aberrant, dialectical form of Persian (called by Masʿūdī al-āḏarīya) as well as standard Persian, and the geographers state that the former was difficult to understand.