Also can someone explain the status or even nationality of Bosnian Muslims that now call themselves 'Bosniaks'. In every name for things in the former Yugoslavia it looks like every ethnicity was included except Bosnians (e.g. Serbo-Croatian language, and then the name of their country, Kingdom of Serbs, Croats and Slovenes).
Recently they came up with the term ‘Bosniak’ to refer to Muslim South Slavs that speak Serbo-Croatian, but before this from what I understand their ethnicity was literally ‘Muslim’, even though in the rest of the world Muslim is just a religion. I’ve read several times that Serbs, Croats and Bosniaks are the same people but created different national identities due to religious differences. Is this true, or is this just nationalistic talk with no foundation in reality? If it’s true, why isn’t there just one ethnicity where they follow different religions? The neighbouring Albanians have no problems being one ethnic group where people follow different religions (Islam, Catholism, Orthodox Christianity, etc). What ethnicity or nationality were Bosniaks prior to becoming Muslim and identifying as 'ethnic Muslims'?
Croatia and Serbia (also Croats and Serbs) existed since early middle ages, before becoming Christian and long before east-west schism. Bosniaks weren't considered separate ethnicity, like Macedonians, by others and weren't allowed to declare as separate people until after WW2. Bosniaks did exist in medieval Bosnia, but it is disputed whether modern Bosniaks are direct descendants of that population. Montenegrins are still not considered as separate ethnicity not just by many Serbs, but by many Montenegrins themselves. Ethnicities aren't something that existed always, they evolve, develop, unite and split apart. The meaning of ethnic identity also changed over time.
In the name of the new country, it seems to reflect the level of political development and national awareness of the three peoples: regional bodies in Slovenia, Croatia and Dalmatia had already proclaimed a five-week "State of the Slovenes, Croats and Serbs" including Bosnia (though the Serbs of Vojvodina proclaimed union with Serbia separately).
Before the Ottoman conquest there was a brief Bosnian kingdom, prior to which the area was sometimes independent, at other times contested by Serbian, Croatian and later Hungarian rulers. The "Muslim" ethnic identification seems a legacy of Ottoman rule which differentiated peoples by religious affiliation rather than national identity, resuscitated by the Tito regime to ease its already difficult ethnic balancing act.