The region of modern Croatia covers a large number of historical and geographical regions of different origins and size. These reflect the political fragmentation of the Croatian lands in the past, and partly also the position of Croatia at the meeting-point of several large, geographical, European components. The best known historical regions are Dalmatia, Slavonia and Istria.
The original Roman province of Dalmatia extended along the east coast of the Adriatic Sea, but also included a significant part of the hinterland, which today belongs to Bosnia and Herzegovina. Byzantine Dalmatia, on the other hand, included only a few coastal towns and neighbouring islands. The region which is considered to be Dalmatia today coincides with the former Venetian territory on the eastern Adriatic in the late 17th and early 18 century. This territory, enlarged by the addition of the Dubrovnik Republic in the 19th century, formed a separate province within the Habsburg Monarchy.
The peninsula in the north of the eastern Adriatic has been called Istria since Roman times. In the 19th century, it formed a separate unit within the Habsburg Monarchy. Although its population was predominantly Croatian, it was only formally annexed to Croatia after the Second World War.
The name Slavonia used to refer to a larger area than today – it covered the entire region north of the Velika and Mala Kapela mountain range. From the 18th century onwards, the name came to be used for the eastern, lowland area of modern-day Croatia, and formed part of the title of the Croatian political core area within the Habsburg Monarchy – the Kingdoms of Croatia and Slavonia.
Other historical and geographical names relate to smaller regions, whose borders are sometimes not clearly defined. The northeast region of Baranja was once part of a Hungarian county of the same name, but has been part of Croatia since 1945. The most eastern part of Slavonia is known as Srijem, and is the relic of a once much larger region, most of which belongs to Serbia today. Lika, Banovina, Kordun and Žumberak are smaller regions, which were wholly or partially under the separately administrated Military Border set up by the Habsburg Empire on what is Croatian soil today. The Military Border was re-integrated with the main Croatian territories in 1881
Some of these names and other names of regions appear in the names of modern counties, the basic units of the administrative division of Croatia, but they have exclusively geographical significance and do not denote any particular political status.
Contemporary regional divisions basically follow the relief division of the country.
The northern, predominantly lowland, part of the country is divided into Eastern and Central Croatia. Eastern Croatia includes the traditional regions of Slavonia, Baranja and the western part of Srijem, i.e. the true lowland area of the Pannonian Plain, bordered by the largest rivers, the Sava, Drava and Danube. This area boasts the optimal conditions for agricultural production. The main regional capital is Osijek, a port on the Drava. Other urban centres include Vinkovci, a transport hub, Vukovar, the largest river port and the only Danube port in the country, Slavonski Brod, Požega and Đakovo.
Central Croatia includes the border areas of the Pannonian Plain and the peri-Pannonian regions of Croatian Zagorje, Međimurje, Pokuplje and Banovina. It is the centre of gravity in terms of population and the economy, with the country's capital, Zagreb. Other urban and regional centres include Varaždin, Čakovec and Krapina in the north part of the region, Karlovac and Sisak in the south and Bjelovar and Koprivnica in the east.
Highland Croatia is the smallest, least populated region, and includes the country’s mountainous area. It is composed of smaller units, particularly the forested Gorski Kotar, the Ogulin–Plaški depression and Lika. Due to the relief and climate, there is little arable land, and only cultures which can withstand severe winter conditions are grown there.
Forestry based on local resources is the dominant branch of the economy. The urban settlements are smaller than in other parts of the country, and the regional centres are Delnice, Ogulin and Gospić.
The coastal part of the country is usually divided into north and south. The Northern Litoral area includes Istria, the most developed tourist region, and the long, narrow Kvarner region below Velebit, with the islands that belong to it. The largest city and regional centre is Rijeka, the largest Croatian port. Other urban centres include Pula and Poreč in Istria, and Senj in the coastal belt below Velebit, and there are also prominent tourist centres such as Rovinj and Opatija, and the island centres of Krk, Rab and Mali Lošinj.
The Southern Litoral forms the historical region of Dalmatia. In terms of climate, landscape and culture, it is a specifically Mediterranean region, within which three parallel belts can be distinguished: the islands, the coast, and the hinterland. The regional centre is Split, the second largest city in Croatia and the largest on the coast. Other important regional and economic centres include Zadar, Šibenik and Dubrovnik on the coast, and Knin and Sinj inland.