Azari or the Ancient Language of Azerbaijan (Persian: آذری یا زبان باستان آذربایجان, romanized: Âzari yâ Zabân-e Bâstân-e Âzarbâyjân) is a treatise written by the Iranian scholar Ahmad Kasravi in 1925, about the history of the Azeri language. This book has been approved by orientalists. In this book, Kasravi, using numerous documents and manuscripts, argues that the Old Azeri language (also known as "Azeri" or "Azari") should not be categorized as a member of the Turkic languages, but as an Iranian language, a descendant of the Median language. This treatise, which was Kasravi's first serious work, was very influential worldwide and led to a new theory in Iran about the existence of Iranian roots in the Azeri language. In the words of the Encyclopædia Iranica: This book enjoyed worldwide scholarly success. The publication of this work can also be considered an affirmation of the indestructible bond of Turkophone Iranians to Iran. Investigating the linguistic relationship of the Iranians of the past was just as much an assertion of their linguistic unity in the future as a means of demonstrating that every Iranian rejoiced in the same, continuous identity. Source: Wikipedia (en)