Southeast Europe
This concept is based on the boundaries of the Balkan peninsula. The countries that have been described as being entirely within the region are: Albania, Kosovo, Bosnia and Herzegovina, Bulgaria, Macedonia and Montenegro.
Balkan Mountains
Geologically, the Balkan Mountains are a "young" part of the Alp-Himalayan chain that stretches across most of Europe and Asia. It can be divided into two parts: the main Balkan Chain and the Pre-Balkans (Fore-Balkan) to the north, which intrude slightly into the Danubian Plain. To the south, the mountains border the Sub-Balkan valleys - a row of 11 valleys running from the Bulgarian border with Serbia east to the Black Sea, separating the Balkan mountains from a chain of other mountains known as "Srednogorie" which includes Vitosha and Sredna Gora.