yeah but also croatia, bosnia, n. macedonia and slovenia. yugoslavia wasn't too bad but you can think of it as a mini soviet union of the balkans. and serbs were kind of like the russians.
also it's complicated, e.g. croatians killed a ton of serbs in ww2 but then became part of yugoslavia where serbs were more dominant. there are also three different religions and a very complicated history. basically the idea behind yugoslavia was to unite all those different ethnicities and relgions but then in the 90s everyone was "fuck that shit, we will create our own small countries now!", and serbs were "nope, we going to fucking kill you if you try", then lots of people died and the US bombed the serbs and that was the end of it.