Book excerpt: Upon the dissolution of the Western Gokturk Khaganate, the declaration of independence and migration movements of the Turkish tribes within her structure as a new migration of tribes deeply affected many layers of world history, especially mainly ethnic and sociological way. However, these migrations leave permanent traces in the northern part of the Black Sea, North Caucasus and the Balkans; their impacts have continued until today. This study examines one of the most controversial issues of history studies: Origins of Gagauz people. There are many different theories about their origin: Are they Turks? Or Greeks? Or Bulgars? In the light of the origin studies of the Gagauz people; the effects of these migrations and the factors other than migrations have been explained.