In early Middle Ages, the territory of modern Bosnia and Herzegovina was divided into many smaller independent states, thus Herzegovina encompasses the regions then known as Humska zemlja (Hum), Travunija, Zahumlje, Primorje, Konavli etc. Westernmost parts of Hercegovina belonged to the Kingdom of Croatia. Since 1320s, all of these lands are a part of the Bosnian kingdom. In a document sent to Friedrich III on January 20, 1448, Stjepan Vukčić Kosača called himself Herzog of Saint Sava, lord of Hum and Primorje, great duke of the Bosnian kingdom. Herzog means count or duke in German, and so the lands he controlled became (much later) known as Herzogs lands or Herzegovina. In 1482 herzog was overpowered by Ottoman forces led by his own son, Ahmed Hercegović, who accepted Islam. In the Ottoman Empire Herzegovina was organized as a province (sandzak) within the state (pashaluk) of Bosnia. The name of the country was changed to Bosnia and Herzegovina in 1853, as a result of a twist of political events. It was part of the Ottoman Empire for less than four centuries before being occuppied in 1878 by Austria-Hungary. This caused great resentment among its Bosniak and Serb populace which together resisted the invaders in smaller flare-ups that ended in 1882.
In the modern Bosnian-Herzegovinian state, Herzegovina is divided between the two entities (see Bosnia and Herzegovina and History of Bosnia and Herzegovina). Republika Srpska doesn't have any special arrangements for Herzegovina. In the Federation of Bosnia and Herzegovina, Herzegovina belongs to cantons Herzegovina-Neretva, West Herzegovina and partially to Herzeg-Bosnia Canton (also known as West Bosnia).
Its western parts are inhabited mostly by Croats, the eastern parts mostly by Serbs, and there is a significant Bosniak population along the flow of Neretva, including cities Mostar, Konjic and Stolac. The population of Herzegovina was mixed prior to the latest Yugoslav War as well as the Second World War, both of which saw ethnic cleansing on a large scale.