Obviously, this was all before the Turkic arrival.
Encyclopedia Iranica quotes
Ibn al-Nadim's book
Al-fihrist in verifying that all the Median and Persian lands of antiquity (including what is today known as
Azerbaijan) spoke one language. And
Tabari in 849 also mentions that poets in
Maragheh recited Pahlavi poetry. Some Azerbaijani poets however, such as
Qatran Tabrizi, used the word "Persian" and "Pahlavi" interchangeably to describe their native language. The historian
Hamdollah Mostowfi even goes as far as describing variants of "Pahlavi" spoken in different areas of Azerbaijan (then part of Greater Persia). In his book
Tarikh Gozideh, he describes eight poets from Azerbaijan, calling them
Ahl-ol She'r Men-al-Ajam (Iranian poets), all Persian by tongue. By now, of course, Dari and Pahlavi had merged into one, as successive dynasties moved from east to west. Suffice it to say that the number of records and documents from Azerbaijan in the Pahlavi language are so numerous that it has left no doubt that this was indeed the native tongue of Azerbaijan before the arrival of the Turks. Many words in the current Azeri vocabulary in fact are of Pahlavi origin. (See studies in
Nashriyeh Adabiyāt of
Tabriz University, by Dr. Mahyār Navābi, year 5 and 6. Also see
Farhang-i Kamāleddin Teflisi,
Ajāyeb al-Makhluqāt by
Najibeddin Hamadāni, and also the books:
Majmal-ol-Tavārikh,
Al-qasas,
Iskandar-Nameh e Qadeem, and others for lists of words.) The current
Turkic Azeri language spoken in Azerbaijan begins its steadly replacement of the old Pahlavi only with the beginning of the
Safavid dynasty's rule in Persia. Earlier, many Turkic speaking nomads had chosen the green pastures of Azerbaijan, Aran and Shrivan for their settlement as early as the advent of the
Seljuqs. However, they only filled in the pasturelands while the farmlands, villages and the cities remained Iranic in language. The linguistic conversion of Azerbaijan went hand in hand with the coversion of the Azeris into
Shiism. From 1501 and the advent of the Safavid dyansty to 1639 and the
Treaty of Zohab between the Ottoman Empire and Persia, perhaps over two million people were forcefully removed from the common battlefields between the two warring states. These included eastern
Anatolia (to include all of Armenia, northern Kurdistan), all of Azerbaijan, Shirvan and Aran (the last two being known presently as the
Republic of Azerbaijan). The Shias were moved east and the Sunnis to the west. The Christians were moved every which way, from Isfahan to Mazandaran, from Marash to Adana. Hundreds of thousands of Turkic speaking Shia nomads from central and eastern Anatolia were resettled in Azerbaijan and Shirvan. Even a larger numbers of Iranic speaking Sunni Azeris/Azaris fled west into the Ottoman Empire from the oppression of the Shia extremism of the early Safavids. Many settled as far afield as Iznik near Istanbul. The famous Iznik glazed pottery and fiance work still has a strong Tabrizi flavor—even today, four hundred years later! Some of these old timer, Iranic speaking, Sunni Azeris moved as far as the new Mughal Empire in India. In short, as Azerbaijan, Shrivan and Aran became steadily more Shia, they also became steadily more Turkic speaking. The process is nearly complete today. Historians report Pahlavi being spoken in
Tabriz as late as the 17th century. (See
Rowdhat ul-Jinan by Hafez Hosein Tabrizi [d997 A.H.], and
Risaleh ye Anārjāni written in 1577). Even the
Ottoman Turkish explorer
Evliya Çelebi (1611–1682) mentions this in his
Seyahatname. He also reports that the elite and learned people of
Nakhichevan and
Maragheh spoke Pahlavi, during his tours of the region As late as 1820s, many neighborhood in Tabriz were still Iranic speaking, although fully Shia by this time. By the late 1800s, the Turkification of Azerbaijan was near completion with the old Iranic speakers found solely in tiny isolated recesses of the mountains or other remote areas (such as Harzand, Galin Guya and Anarjan). Even the heavily populated Kurdish tribes of Azerbaijan, most importantly the great
Qashqai tribe switched from Kurdish to Turkic Azeri in the course of the 19th century as they accept Shiism for their religion. The old timer Shaqaqis still can muster some Kurdish, while the newer generations are fully assimilated. The old Iranic,
Pahlavi based language of Azerbaijan, is now extinct, unless one considers
Harzandi and other
isoglosses to be remnant of it.