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.
After his failed rebellion in Ankara, Mehmet Bey died in a conflict against Seljuq-Mongol troops.
^The Encyclopaedia of Islam, Volume 4, Brill, 1954, p. 620.
^Acem kültürünün te'sirleri altında yetişen me'murlar devlet işlerinde de Fars dilini kullanmakta idiler; Farsçanın resmî dil olarak bu kuvvetli tehakkümü, Karaman Beyi Mehmed Bey'in Konya'yı istilâsına kadar sürdü., Mehmet Fuat Köprülü, Türk Edebiyatında ilk Mutasavvıflar, 6. Basım, Diyanet İşleri Başkanlığı, 1987, p. 234. (in Turkish)
^ abAgop Dilaçar, Devlet Dili Olarak Türkçe, Türk Dil Kurumu Yayınları, 1962, p. 14. (in Turkish)
^Taqī Āzādarmakī, T. Azadarmaki, Contact Des Langues Dans L'Espace Arabo - Turco - Persan I: Arabo - Turco - Persan I, Peeters Publishers, 2005, ISBN978-2-909961-35-4, p. 90.(in French)