Croatia proper is a geographic region of Croatia that encompasses territory around Zagreb, located between Slavonia in the east and the Adriatic Sea in the west. Its exact borders are determined ambiguously, and the extent of the region is defined differently by various sources. The border with Slavonia to the east was variously defined throughout history, depending on the political divisions of Croatia. Croatia proper roughly corresponds to the area of Zagreb and ten Croatian counties: Bjelovar-Bilogora, Karlovac, Koprivnica-Križevci, Krapina-Zagorje, Lika-Senj, Međimurje, Primorje-Gorski Kotar, Sisak-Moslavina, Varaždin, and Zagreb County.