I asked becouse it seems like serbian people is the oldest and that others come from them acctually. Maybe I got the wrong impression. I also read few different explanations. For example, I found my lastname on that list Cvetinov posted, while I read from one other source that my surname comes originally from Istra (Croatia).
There are too many conflicting sources. Some say Croats come from Celts, some that we are Slavs and that all Slavs originate in Ukraine. Many people look at things too subjectivly, mostly in Croatia and Serbia, so they make up different teories to fullfill their ideas, I think.