Khazars were a branch of Gog-Turks who built an enormous empire in the 6th century after they were defeated by the Chinese in northeast and central Asia. The ancestral Turks were an Asian people from eastern Siberia (Their kin are still found in eastern Siberia, still speaking Turkic languages)
The Gok-Turks expanded their territory toward the west, cross the Volga and conquering what is today Ukraine.
The rulers of the Khazar Empire, a branch of the Go-Turks, decided to converted to Pharisee Judaism in the 9th century. And you know the rest of the story.
Other Turkic tribes who converted to Islam in Central Asia migrated further west into Caucasus and the territory of modern Turkey in order to escape the approaching Mongolian army in the 13th century.
This was an interesting article from a Journalist who volunteered to fight in the Russian front. He had a lot of insights on how the war is being fought and how the future of warfare is going to. Very illuminating account by him.