By the end of the Middle Ages, migration of Eastern Orthodox Christians towards Austrian lands was intensified due to expansion of the Ottoman Empire in various regions of Southeastern Europe.
Exiled members of Eastern Orthodox royal and noble families were welcomed by Habsburg rulers, who granted them new possessions.
Since those regions were inhabited by Eastern Orthodox population, Habsburg court was inclined to adopt policy of religious tolerance.
[3] Emperor Leopold I issued several charters (1690, 1691, 1695) to Eastern Orthodox Serbs, who sided with Habsburgs during the Vienna War (1683-1699), granting them religious freedom in the Monarchy.
[6] During the 18th century, Eastern Orthodox communities in major Austrian cities were consisted mainly of ethnic Greeks, Serbs and Romanians.