Thrace (demonym Thracian ; , Thraike; modern , Thráki; , Trakija ) is a historical and geographic area in southeast Europe, centered on the modern borders of Bulgaria, Greece, and Turkey. In antiquity, it was also referred to as Europe, prior to the extension of the term to describe the whole continent. As a geographical concept, Thrace designates a region bounded by the Balkan Mountains on the north, Rhodope Mountains and the Aegean Sea on the south, and by the Black Sea and the Sea of Marmara on the east. The areas it comprises are southeastern Bulgaria (Northern Thrace), northeastern Greece (Western Thrace), and the European part of Turkey (Eastern Thrace). The biggest part of Thrace is part of present-day Bulgaria. In Turkey, it is also called Rumeli. The name comes from the Thracians, an ancient Indo-European people inhabiting Southeastern Europe.