Vlachs (English pronunciation: /ˈvlɑːk/ or /ˈvlæk/) is a historical term used for Eastern Romance-speaking peoples in the Balkans and Eastern Europe; several modern peoples descending from the Romanized population in present-day Romania and Moldova, the southern Balkan Peninsula and south and west of the Danube. They were identified during the 11th century (when they were described by George Kedrenos), and their prehistory during the Migration Period is a matter of scholarly speculation. According to one origin theory, the Vlachs originated from Latinized Dacians. According to some linguists and scholars, the Eastern Romance languages prove the survival of the Thraco-Romans in the lower Danube basin during the Migration Period and western Balkan populations known as "Vlachs" also have had Romanized Illyrian origins. Nearly all central- and southeastern European nations (Hungary, Ukraine, Serbia, Croatia, Macedonia, Albania, Greece and Bulgaria) have native Vlach (or Romanian) minorities; in other countries, the Vlachs have assimilated to the Slavic population. The term was also commonly used for shepherds. Today, the Eastern Romance-speaking communities number 24,187,810 people.
Vlach (Serbo-Croatian: Vlah; plural: Vlasi) (Ottoman Turkish: Eflak; plural: Eflakân) was a social class within the Ottoman Millet system, composed largely of Christian nomadic and semi-nomadic pastoral populations of genuine Vlachs and Serbs.
Following the Ottoman conquest of the Balkans, the Vlachs, being both Orthodox and Catholic, and still a largely nomadic and semi-nomadic pastoral non-Slavic-speaking people; played a dual role in the relations with the new Ottoman ruler. Although a few of the Orthodox Vlachs and part of the Catholic Vlachs from Duklja and Bosnia fled before the invading Ottoman armies, to Christian lands in the West (i.e. Croatia and abroad); the remaining of them, both Orthodox in the central Balkans and Catholics in Herzegovina and Duklja, welcomed with joy the new situation created, since the conquerors vouchsafed to them vast ranges for themselves and their cattle and promised to improve their social position. It thus propitiated special arrangements between the Turks and the Vlachs, who in turn, while preserving their religion (excepting some, largely high-ranking members of society, who converted to Islam in order to secure for themselves and their families special privileges and prominent administrative positions from the Ottoman authorities), placed themselves in the Sultan's service; all this made possible that the Vlachs would come to form a considerably privileged class within the Millet system in the Ottoman Empire, compared to the class of the Reaya, for more than a century. In adittion, with the beginning of Ottoman rule, within this social class also came to be included other Vlach-like (pastoral semi-nomad) populations, such as cattle-breeding Orthodox Serbs; who also were serving as Ottoman army-attached garrisoned auxiliary units in Hungary, during the 16th century, in large numbers, jointly with the Vlachs.