or Kumiss. Fermented mare's milk used as a beverage by the Tartar tribes of Central Asia. A slightly alcoholic drink of a similar kind is made with great ceremony in Siberia. It consists of slightly sour cow's milk, sugar, and yeast. (Russian, kumuisu.)
“Kumiss is still prepared from mare's milk by the Calmucks and
Nogais, who, during the process of making it, keep the milk in constant
The ceremony of making it is described at full length by Noel, in the Dictionnaire de la Fable, vol. i. 833-834.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Koumiss from Infoplease: