Koča's frontier (Serbian: Кочина крајина/Kočina krajina) refers to the Serbian territory established in the Sanjak of Smederevo, Ottoman Empire, during the Austro-Turkish War (1787–91). The Habsburg-organized Serbian Free Corps, among whom were prominent Koča Anđelković (hence the historiographical name), initially held the central part of the sanjak, between February and September 7, 1788; after the Austrians entered the conflict the territory was expanded and became a Habsburg protectorate under military administration, called Serbia (German: Serbien). After the Austrian withdrawal and Treaty of Sistova (1792), the territory was regained by the Ottomans.