Technical Abstract: Fermentative microorganisms in the yeast genera Debaryomyces, Hyphopichia, Kluyveromyces, Lachancea, Saccharomyces, and Wickerhamomyces (and in the bacterial genus Lactobacillus) have been isolated from a variety of fermented beverages. These same microorganisms were very likely unknowingly utilized for beverage production by a wide variety of ancient peoples, especially those known as Indo-Europeans. Historical examples of beverages (ale, beer, kvass, koumiss, mead and wine) consumed in ancient Indo-European cultures are attested by Indo-European and Proto-Indo-European cognates for these beverages, and by results of chemical analyses of residues on ancient pottery. A historical account is followed by descriptions of analogous uses of fermentative microorganisms in contemporary beverage production for modern kvass, koumiss and mead. Beverages initially produced by ancient Indo-European nomads are now the focus of probiotic beverage production, and the fermentative microorganisms are the focus of numerous investigations by food scientists. Modern, extensive collections of microbial germplasm (both governmental and private) contain these microorganisms. Numerous examples are provided, specified by name of the collection, species name of the microorganism, accession number, and source of isolation.