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Lingua franca

An Azerbaijani koine served as a lingua franca throughout most parts of Transcaucasia except the Black Sea coast, in southern Dagestan, the Eastern Anatolia Region and all over Iran from the 16th to the early 20th centuries, alongside cultural, administrative, court literature, and most importantly official language (along with Azerbaijani) of all these regions, namely Persian. From the early 16th century up to the course of the 19th century, these regions and territories were all ruled by the Safavids, Afsharids, and Qajars until the cession of Transcaucasia proper and Dagestan by Qajar Iran to the Russian Empire per the 1813 Treaty of Gulistan and the 1828 Treaty of Turkmenchay. Per the 1829 Caucasus School Statute, Azerbaijani was to be taught in all district schools of Ganja, Shusha, Nukha (present-day Shaki), Shamakhi, Quba, Baku, Derbent, Yerevan, Nakhchivan, Akhaltsikhe, and Lankaran. Beginning in 1834, it was introduced as a language of study in Kutaisi instead of Armenian. In 1853, Azerbaijani became a compulsory language for students of all backgrounds in all of Transcaucasia with the exception of the Tiflis Governorate.