Until the beginning of the 20th century, Armenians continued to form the largest ethnic group (but not religious majority) in most of Ottoman Armenia. The demographics of the region changed considerably due to the Ottoman Empire's policy of settling Muslim refugees from the Balkans during the Balkan wars into the region, and the emigration of Ottoman Armenians to Russian Armenia, the latter of which had been ongoing since the mid-19th century, when most of Iranian Armenia had been annexed by the Russian Empire.