In the article information is cited about the ethnic composition of the population of Bessarabia, their numbers, the history of the appearance of the ethnic groups in the given territory. The cohabitation of the various ethnic groups in Bessarabia, as part of the Russian Empire, promoted not only the mutual enrichment of cultures but also led to the formation of a particular polyethnic commonality - the Bessarabians, distinguished by a high degree of passiveness, «imperial» consciousness and mentality, distinguishable from the Rumanian although Rumanians are closely related to the Moldavians in an ethno-cultural sense. This commonality clearly showed itself during the years of the Revolution, Civil War, Rumanian Occupation and WWII. During that period of time, the ethnic groups in Bessarabia could preserve their own ethno-cultural identity. It was here that the Orthodox Turkic-speaking immigrants from beyond the Danube could form into an independent ethnos - the Gagauz.