The Macedonian Question ? 
The Ottoman conquest of Macedonia, which was completed during the 15th century, caused major changes in the population of the Balkans in general and of Macedonia in particular. The Christian population began to abandon the plains and take refuge in the mountains, while the economic and intellectual elite fled to the West. Simultaneously, Turkmen populations (Uruks) moved in, settling principally in Central Macedonia. Those Christians who found themselves unable to bear the harshness of the Ottoman yoke and the humiliations to which they were subjected embraced Islam. Known as 'Valaades', these Greek-speaking Muslim populations were still to be found in some parts of the Kozani area until the liberation of Macedonia in 1912. Later, with the exchange of populations of 1923-24, they shared the fate of their co- religionists and settled in Turkey.
In and after the 17th century the situation stabilized somewhat and the Greek populations returned to the plains. Since the vast Ottoman Empire had no borders, there were widespread population movements. As Professor Vakalopoulos notes in his History of Macedonia (p. 7):
"Muslims and Christians availed themselves of the opportunity to move freely in every direction, towards Macedonia and inside it, and they interbred and intermingled with the local populations, creating new settlements, new living conditions and new problems. While on the one hand Turks entered and settled in various parts of Western, Central and Eastern Macedonia, on the other hand the Greeks of Thessaly and primarily of Macedonia and Epirus moved on, advancing peacefully northwards into Serbia, Austro-Hungary, Bulgaria and Romania, forming Greek colonies in the cities of those countries, founding towns and villages or injecting new blood into very ancient nuclei ofpopulation. The South Slavs and, above all, the Bulgars, moved south in search of work, revitalizing the remnants of the old Slav colonies of the Middle Ages in some parts of Macedonia or forming new settlements of their own."
In this way, the Slav element gained in strength while the Slavic-Bulgarian language gained ground in the northern zone (what today is Yugoslavian Macedonia) and in the central area. After the 18th century, however, the Greek element flourished in a multitude of ways in the economic, social and educational sectors, thus leading to the complete domination of the area by Greek intellectual and cultural influences. With the support and guidance of the Greek clergy, the Christian masses of Macedonia acquired a consciousness of their Greek identity. It is characteristic that numerous Slav-speaking Christians sent their children to Greek schools, fought against the Ottoman Empire during the Greek War of Independence of 1821-28 and later took part, throughout the 19th century, in all the Greek risings in Macedonia, fighting for the unification of Macedonia with the free Greek State.
