A larger-scale movement of Greek-speaking peoples in the Ottoman period was Pontic Greeks from northeastern Anatolia to Georgia and parts of southern Russia, particularly the province of Kars Oblast in the southern Caucasus after the short-lived Russian occupation of Erzerum and the surrounding region during the 1828–29 Russo-Turkish War. An estimated one-fifth of Pontic Greeks left their homeland in the mountains of northeastern Anatolia in 1829 as refugees, following the Tsarist army as it withdrew back into Russian territory (since many had collaborated with—or fought in—the Russian army against the Muslim Ottomans to regain territory for Christian Orthodoxy). The Pontic Greek refugees who settled in Georgia and the southern Caucasus assimilated with preexisting Caucasus Greek communities. Those who settled in Ukraine and southern Russia became a sizable proportion of cities such as Mariupol, but generally assimilated with Christian Orthodox Russians and continued to serve in the Tsarist army.
