Herzegovina
Herzegovina ( or ; Serbo-Croatian: "Hercegovina", Херцеговина, ) is the southern region of Bosnia and Herzegovina. While there is no official border distinguishing it from the Bosnian geographical region, it is sometimes asserted that the borders of the region are Dalmatia to the southwest, Montenegro to the east, Mount Maglić to the northeast, and Mount Ivan to the north. Measurements of the area range from , or around 22% of the total area of the present-day country, to , around 24% of the country.
East Herzegovina
East Herzegovina (, Источна Херцеговина) 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 (see Serbs of Bosnia and Herzegovina). 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 (the Duchy of St. Sava and Sanjak of 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 (Regija Trebinje/).