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 ; 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, 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 addition, with the beginning of Ottoman rule, within this social class also came to be included other Vlach-like populations, such as cattle-breeding Orthodox Serbs;. Serbs in Ottoman Hungary in great numbers served as Martolos, which are largely recruited from the Vlach and Vlach like population.
Service
During the early history of the Ottoman Empire in the Balkans, there was Vlach people members of military class living in Serbia and Macedonia which had the same rights as Muslims. They might have been the descendants of Christians but their origin is not entirely clear. Due to their experience in carrying goods and the skill and speed with which they crossed the mountain regions; the Turks began to take advantage of it by employing them as auxiliary troops, thus entrusting to them the conveyance of military supplies, the carrying out of spying operations and quick looting-sorching raids in enemy Christian territory, and the patrol of mountain gorges and boundaries in general. In addition, they always accompanied the Ottoman armies in their expeditions throughout the Balkans, up to the North-West, in whole communities; being intended for populating the newly conquered territories as border military colonies, called katun or džemaat ; at the head of which there was a katunar or primikur. They also formed important as well as highly numbered Christian military garrisons attached to the Ottoman army, in the newly conquered towns. In exchange for their regular duties, they were granted privileges which were denied to all other Zimmîs by the Šerijat or Islamic Law; for example, as they served regularly as Ottoman auxiliary troops, they were allowed to bear arms and to ride horses. This rewarding privileges were also extended to the economic sphere; these communities were largely exempted of paying any tax but only that of an annual rent of one gold 'ducat' or 'florin' to pay by each one of their households, hence coming to be called as "Florin" or "Ducat Vlachs". At the same time, great Turkish and Slavic Muslim landholding military nobles often brought with them significant quantities of these Vlachs, in order that they farmed their lands.
The Rüsûm-i Eflakiye was a tax on Vlachs in the Ottoman Empire. Vlachs in the Balkans were granted tax concessions under Byzantine and Serb rulers in return for military service; and this continued under Ottoman rule. Instead of some of the customary taxes, they paid a special "Vlach tax", Rüsûm-i Eflakiye: One sheep and one lamb from each household on St. Georges Day each year. Because Vlachs were taxed differently, they were listed differently in defters.
