Old Tatar language
The Old Tatar language (İske imlâ: يسكى تاتار تلى (translit. İske Tatar Tele)) was a literary language used among the Muslim Tatars from the Middle Ages till the 19th century. Was a regional variety of Turki, a written Turkic language used throughout the Muslim Turkic world.
Old Tatar is a member of the Kipchak (or Northwestern) group of Turkic languages, although it is partly derived from the ancient Bolgar language (the first poem, considered to be written by Qol Ghali in Old Tatar dates back to Volga Bulgaria's epoch). It included many Persian and Arabic loans.
In its written form the language was spelled uniformly among different ethnic groups, speaking different Turkic languages of the Kipchak group, but pronunciation differed from one people to another, approximating to the spoken language, making this written form universal for different languages. The main reason for this universal usage was that the principal differences between the languages of the Kipchak group are in the pronunciation of the vowels, which was not adequately represented by the Arabic script.
The language formerly used the Arabic script and later its variant İske imlâ. The Old Tatar Language is a language of Idel-Ural poetry and literature. With the Ottoman Turkish, Azeri, Kipchak, Uigur  and Chagatai, they were the only Turkic literary languages used in the Middle Ages. It was actively used in publishing until 1905, when the first Tatar newspaper started being published in modern Tatar, which until then had been used only in a spoken form.
- (Tatar) "İske Tatar ädäbi tele/Иске татар әдәби теле". Tatar Encyclopaedia. Kazan: The Republic of Tatarstan Academy of Sciences. Institution of the Tatar Encyclopaedia. 2002.