The Transitional geomorphological region encompasses the territory between the Balkan Mountains and the Rilo-Rhodope Massif and has complex, mosaic relief composed mainly of medium-high and low mountains, valleys and plains. The altitude decreases from west to east. This region includes the Sub-Balkan valleys; the mountains and valleys of the Kraishte region, such as Ruy Mountain, Miloslavska planina and Milevska Planina; the mountains Lyulin, Vitosha, Sredna Gora, Strandzha and Sakar; the Dervent Heights; as well as the fertile Upper Thracian Plain. The highest point is Cherni Vrah in Vitosha at 2,290 m.