The Serb-administered Republika Srpska area of the country of Bosnia and Herzegovina has been using its own stamps since 1992. The first stamps used were stamps of the then-splintering Yugoslavia, with Cyrillic overprints reading Република Српска (Republika Srpska, or Serb Republic).
After heavy fighting, the Washington Accords split the country into two parts; the Croat-administered area, based in Mostar, issues its own stamps as well. The Serb-administered area, actually made up of two non-contiguous geographic areas, is based in Sarajevo officially, but in fact in Banja Luka.
The postage stamps of Republika Srpska use Cyrillic, usually in capital letters — РЕПУБЛИКА СРПСКА — and usually no English, making them slightly more difficult to identify for collectors who aren’t familiar with the Cyrillic alphabet than many other countries.