WEast Herzegovina is the eastern part of the historical Herzegovina region in Bosnia and Herzegovina, east of the Neretva river, part of the Republika Srpska entity. Major towns are Trebinje, Nevesinje, Foča and Bileća, predominantly inhabited by ethnic Serbs. West Herzegovina is the western part, west of the Neretva river, and is today administratively part of the Herzegovina-Neretva Canton and West Herzegovina Canton, predominantly inhabited by ethnic Croats, located in the Federation of B&H entity. The easternmost parts of historical Herzegovina lie in Montenegro, in so-called "Old Herzegovina", which became part of the Principality of Montenegro in 1878. In 1991, local ethnic Serbs of the region declared the territory of SAO East Herzegovina independent and joined other Serb territories into Republika Srpska by 1992. The meso-region has since been named Trebinje Region.
WKnešpolje or Knežopolje (Кнежопоље) is a region in northwestern Bosnia and Herzegovina. It is the northwestern part of the Potkozarje geographical region, and includes a region stretching from Prijedor, Kozara mountains, Bosanska Dubica, the Una river and Bosanska Kostajnica. Its name is derived from knez and polje (field).
WLijevče, also the Lijevče field, is a small geographical region in northern Bosnia and Herzegovina; a plain situated between the rivers Sava and Vrbas, and Mount Kozara. It includes settlements part of Gradiška, Srbac and Laktaši, in the Banja Luka Region of the Republika Srpska entity. It is part of the wider Bosanska Krajina historical region.
WOsat is a region in central Podrinje, in Bosnia and Herzegovina. It is situated between the towns of Višegrad and Srebrenica, and includes parts of the municipalities of Bratunac and Srebrenica, in the Republika Srpska entity. It is part of the wider Birač region.
WPodrinje is the Slavic name of the Drina river basin, known in English as the Drina Valley, located in Bosnia and Herzegovina and Serbia.
WPosavina is a geographical region that stretches along the Sava river, encompassing only the inner areas of the Sava river basin, that are adjacent or near to the Sava river itself, in Croatia, Bosnia and Herzegovina, and Serbia.
WRomanija is a mountain, karst plateau, and geographical region in eastern Bosnia and Herzegovina, including numerous villages and towns, such as Pale, Sokolac, Rogatica and Han Pijesak. Its highest point is Veliki Lupoglav.