Slavonia (/sləˈvoʊniə/; Croatian: Slavonija) is, alongside Dalmatia, Croatia proper, and Istria, one of the four historical regions of Croatia. Taking up the east of the country, it roughly corresponds with five Croatian counties: Brod-Posavina, Osijek-Baranja, Požega-Slavonia, Virovitica-Podravina and Vukovar-Srijem, although the territory of the counties includes Baranya, and the definition of the western extent of Slavonia as a region varies. The counties cover 12,556 square kilometres (4,848 square miles) or 22.2% of Croatia, inhabited by 806,192—18.8% of Croatia's population. The largest city in the region is Osijek, followed by Slavonski Brod and Vinkovci. It is located in the Pannonian Basin, largely bordered by the Danube, Drava and Sava rivers. In the west, the region consists of the Sava and Drava valleys, and the mountains surrounding the Požega Valley, and plains in the east.