Kumis is a fermented dairy product traditionally made from mare milk or donkey milk. The drink remains important to the peoples of the Central Asian steppes, of Turkic and Mongol origin: Kazakhs, Bashkirs, Kalmyks, Kyrgyz, Mongols, and Yakuts. Kumis was historically consumed by the Khitans, Jurchens, Hungarians, and Han Chinese of North China as well.

Fermented milk products or fermented dairy products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been made by fermenting milk with lactic acid bacteria such as Lactobacillus, Lactococcus, and Leuconostoc. The fermentation process increases the shelf life of the product while enhancing its taste and improving the digestibility of its milk. There is evidence that fermented milk products have been produced since around 10,000 BC. A range of different Lactobacilli strains has been grown in laboratories allowing for many cultured milk products with different flavors and characteristics.