Historically, the country of Macedonia once consisted of two parts: Lower Macedonia, the alluvial plain watered by the rivers Haliacmon; and the Axius, situated immediately north of Mount Olympus. Today this area is part of modern Greece. Upper Macedonia is a mountainous, forested region. The northern part of this area constitutes the Former Yugoslav Republic of Macedonia. Although the two landscapes are different, they share a continental climate with cold winters. This climate makes the Macedonian vegetation different from the rest of the Aegean region.