As a country with more history than geography, Serbia has had its own migrations, generally into the direction of Vojvodina (the first one being during the turkish rule) from the poorer or less free parts, with some exceptions.
Those happening in XX century were even officially called colonizations, and would happen as an aftermath of major wars. After WWI, the king would give some lland to volunteers; the serbian volunteers from Brazil even founded their own village, which was, until recently, called Brazilija. The colonists would mostly come from poorer areas in the mountains - mostly serbian areas of Croatia, Bosnia and Herzegovina, Montenegro.
After WWII the second, larger, wave came from these same areas, generally into Vojvodina, and were given the abandoned german houses. The folklore built around the culture shock is still alive and the stories are circulating (of taking out the hardwood floors and building a fireplace in the middle of the largest room, as they were accustomed at home, or not understanding the dangers of lack of irrigation in the flatlands, as the idea of a flood was totally alien to tenth generation of highlanders etc etc).
The more interesting part is the reaction of the children and grandchildren of this second wave, when they started hosting their cousins from the mountains in the third wave, after the internal wars of the nineties.
The culture is mostly smoothed over by now. The young of today don't even have much of the old accent or vocabulary, except in the villages where the colonists are the majority.