The region extends northwards from the Aegean Sea primarily through the lands of Kosovo, Macedonia, Ruthenia, Serbia and Slavonia. A tongue of the forest reaches into the central highlands of upland Greece (eastern Epirus and western Thessaly). The climate is humid subtropical, with wet winters.
Forests are dominated by oaks and beech mixed with pine, fir and spruce. Biodiversity includes wisent, wolves, lynx, bears (brown), foxes and stags, eagles, owls and vulture.