Kingdom of Bosnia
In a document sent to Frederick III on January 20, 1448, Stjepan Vukčić was titled "Herzog (duke) of Saint Sava, lord of Hum and Littoral, Grand duke of the Kingdom of Bosnia". Following the Ottomans conquest and fall of Bosnian Kingdom, Duchy of Saint Sava (also known as the "Duchy of Hum") became known as "Herzog's lands" or "Herzegovina".