List of lingua francas
Turkish is still in use and widely spoken in several areas formerly part of the Ottoman Empire and may be understood by older people in other parts of the Middle East.
Firman of Karamanoğlu Mehmet Bey
Agop Dilaçar, who is known for his works on the Sun Language Theory, claimed that Mehmed Bey might have declared Turkish the official language of the state. According to Dilaçar, in his firman dated 13 May (15 May ?) 1277, he ordered that "from that day forward, in the council, in the dervish lodge, in the court, in the assembly, in the square, no language but Turkish should be spoken".
Before him, the Seljuq elite in Anatolia used Persian in literature and Arabic in government and science. The Turkmen, however, could not understand these languages.