Languages of the Ottoman Empire
The Ottomans had three influential languages: Turkish, spoken by the majority of the people in Anatolia and by the majority of Muslims of the Balkans except in Albania, Bosnia, and various Aegean Sea islands; Persian, initially used by the educated in northern portions of the Ottoman Empire before being displaced by Ottoman Turkish; and Arabic, used in southern portions of the Ottoman Empire; Arabic was spoken mainly in Arabia, North Africa, Mesopotamia and the Levant. Throughout the vast Ottoman bureaucracy Ottoman Turkish language was the official language, a version of Turkish, albeit with a vast mixture of both Arabic and Persian grammar and vocabulary.
Croat Muslims
In 1585, a traveler and writer Marco A. Pigaffetta, in his "Itinerario" published in London, states: "In Constantinople it is customary to speak Croatian, a language which is understood by almost all official Turks, especially military men." Crucially though, the lingua franca at the time among Slavic elites in the Ottoman Empire was still Old Church Slavonic. For Italians traveling through to Istanbul, the language of the Slavic Croats was often the only exposure they had to any of the Slavic languages; indeed, Bulgarian and Macedonian dialects were far more common in Istanbul than Croatian.