That's why I asked about a possible, i.e. plausible name for a formably South Slavic kingdom. Why shouldn't history unfold in such a way that the Balkan countries unite into a single kingdom?
Here is what the problem is: there is no plausible South Slavic unification.
When people get desperate then they end up looking for just about anything, and thus the idea of "Illyria" as formable country for quasi Yugoslavia was born on this forum.
An idea that makes no sense what so ever.
That would be like having Dacia or Thracia formable instead of Romania, Scytia instead of Russia, or Babylon (or whatever) instead of Persia.
Bottomline is Balkan people were divided by religion and civilizational influences, before the late era of nationalism, there was no possibility for any kind of political project that would result in their unification.
Even the first Yugoslavia was far from being a "unification country", it was basically a Serbian tyranny over everyone else with the western blessing, because such situation suited their geo strategic interests.