As the 19th and 20th centuries arrived, the Ottomans started facing the growing problem of nationalism and identity. With the age of multicultural Empires united by the legitimacy of the monarchy was ending, Nationalism tore the Empire apart and put them in the precarious position of OTL. While Tanzimat and other reforms started bringing the Empire into the modern age, the National identity was necessary to keep it united into the coming era. One of the options was to emphasize the Sultan’s role as Caliph, uniting the Empire by the force of Islam. But such option would dump fuel into the fire of the Balkans (except some exceptions like Albania and Bosnia that couldn’t be kept either way if the rest of Rumelia seceded), and would further provoke Russia, especially since it would bring discrimination and even genocide to Christian communities of the Sublime Porte. Then, there was the path focusing on cultural diversity and unity under the House of Osman. The problem with this is the Empire forced to spread its attention and resources trying to keep rival groups from tearing each other apart inside the Empire. Then there is the obvious no no of Pan-Turanism. Restricting the privileges and identity of the Empire in Anatolia is not a wise choice as was proven IOTL by the Young Turks, as that would alienate both the Balkans and the Arabs. The challenge here is: Find an national identity for the Sublime Porte. What does it mean to be “Ottoman” instead of Turkish or Serb ? With an PoD set on the First Serbian Rebellion, create something that could keep an massive multicultural Empire with rival religions and ethnicities united into the 20th century. Territorial losses are acceptable only in Northern Africa, Caucasus, and Romanian Principalities.