Macedonia is a geographic and administrative region of Greece, in the southern Balkans. Macedonia is the largest and second-most-populous Greek region, with a population of 2.38 million in 2017. The region is highly mountainous, with most major urban centres such as Thessaloniki and Kavala being concentrated on its southern coastline. Together with Thrace, and sometimes also Thessaly and Epirus, it is part of Northern Greece. Greek Macedonia encompasses entirely the southern part of the region of Macedonia, making up 51% of the total area of the region. It also contains Mount Athos, an autonomous monastic region of Greece. Macedonia forms part of Greece's national frontier with three countries: Bulgaria to the northeast, North Macedonia to the north, and Albania to the northwest. Macedonia incorporates most of the territories of ancient Macedon, a kingdom ruled by the Argeads, whose most celebrated members were Alexander the Great and his father Philip II. Before the expansion of Macedonia under Philip in the 4th century BC, the kingdom of the Macedonians covered a region corresponding roughly to the western and central parts of the region of Macedonia in modern Greece. The name Macedonia was later applied to a number of widely-differing administrative areas in the Roman and Byzantine empires. With the gradual conquest of southeastern Europe by the Ottomans in the late 14th century, the name of Macedonia disappeared as an administrative designation for several centuries and was rarely displayed on maps. The name Macedonia revived in the nineteenth century as a geographical term, with the rise of nationalism in the Ottoman Empire, and for educated Greeks it corresponded to the ancient historical land. The economic ascent of Thessaloniki and of the other urban centres of Macedonia coincided with the cultural and political renaissance of the Greeks.