Sredna Gora (Bulgarian: Средна гора [ˈsrɛdnɐ ɡoˈra]) is a mountain range in central Bulgaria, situated south of and parallel to the Balkan mountain range (Stara Planina) and extending from the Iskar River to the west and the elbow of Tundzha north of Yambol to the east. Sredna Gora is 285 km long, reaching 50 km at its greatest width. Its highest peak is Golyam Bogdan at 1,604 m (5,262 ft). It is part of the Srednogorie mountain chain system, together with Vitosha (the highest massif), Plana (mountain), Lyulin Mountain, Greben (mountain), Viskyar Mountain, etc.
Source: Wikipedia