The first century of the Ottoman period was marked by a decline in the Christian population and by the arrival of new inhabitants. While the Christians withdrew to the western and southern mountains and Halkidiki, Ottoman and Yuruk Turks compensated somewhat for their departure by moving to the plains of central and north-western Macedonia.
In the late 15th century, Jews of German, Hungarian, Spanish and Portuguese origin settled in Thessaloniki. In the 16th century Jewish communities were founded in Skopje, Monastir, Serres, Kavala, Drama and other towns.
During the same period, Greek-speaking Christians, as well as the Vlachs of the Pindos mountain range, began to move down from the mountains into the plains, becoming more urbanized in the process.
The 17th century saw the conversion to Islam of large numbers of Christians (mainly in western Macedonia) and of Jews in Thessaloniki. This considerably boosted the strength of the Muslim population.
Generally, the pre-Revolutionary period was characterized by the slow rate of population growth throughout the region, with the possible exception of the western areas and the cities. It was also marked by an astonishing intermingling of language groups, which however posed no threat to the predominance of Greek in southern Macedonia.