Vlasina is a mountainous region of southeastern Serbia. It is a border area to Bulgaria, a region of the Rhodopian Serbia, with old rocks and mountains. Its most prominent landforms are eponymous Vlasina River and Vlasina Lake. It corresponds to the territories of municipalities of Crna Trava, Vlasotince and Surdulica. The region consists of fours smaller, micro-regions: Crna Trava, , Lužnica and Vlasotince. Near Vlasotince, remains of the ancient volcanic eruptions are quite visible.