One from the Pop Demand Mod, as the Ottoman Empire. You start off with only Turkish culture accepted, and this naturally leads to lots of nationalism later on, and can lead to you breaking up. But if you choose a particular decision, you can start accepting other cultures - and you have the option to accept some who had been traditionally been oppressed, and can do so for three separate cultures. If you accept the Bosniak, Albanian and Bulgarian cultures, you also can accept Greek and Romanian culture, and add what would later become Romania and Greece as cores to the empire, all accepted as brothers to the Turks. There's also events to add Armenian and Kurdish cultures in there. Combine with this the Secularized or Atheist religious policy, and you end up with an empire based on the acceptance of all cultures in it, all religions accepted, and all working to let them know they are a part of the same nation, brothers in arms.