Kumiss is a fermented drink made from mare’s milk, with a tart, slightly fizzy taste and a low alcohol content. It has been a staple beverage across Central Asia, Russia, and Eastern Europe for more than 2,500 years, and it remains culturally significant in many of those regions today.
Origins and Cultural Significance
The word “kumiss” (also spelled koumiss or kumys) likely traces back to a tribe that lived beside the Kuma River in the grasslands of Central Asia. The drink is deeply tied to nomadic horse-herding cultures, where preserving the nutrients in mare’s milk through fermentation was a practical necessity. Scythian tribes in Central Asia and guards in southeastern Russia were making kumiss more than 2,500 years ago, and the drink gained further popularity in China during the Han Dynasty (202 BC to AD 202) and Yuan Dynasty (AD 1271–1368).
In Turkish-speaking cultures, kumiss holds an especially important place. Known historically as “Turkistan Boza,” it carried religious significance among early Turkic peoples and was believed to increase courage, inspire poets, and cure illness. The 14th-century Arabian traveler Ibn Battuta described it in his writings: “after meals, they consumed this drink called kumis, made of mare’s milk.” Today, kumiss consumption remains common across Central Asian countries like Kazakhstan, Kyrgyzstan, and Mongolia (where it’s called airag).
How Kumiss Is Made
Traditional kumiss production is straightforward but requires specific conditions. Fresh mare’s milk is poured into a container, historically a bag made from horse skin, and inoculated with a starter culture from a previous batch. The milk is then stirred or churned repeatedly over the course of fermentation. This agitation is important because it distributes the microbes evenly and helps create the drink’s characteristic light, effervescent texture.
What makes kumiss distinct from yogurt or cheese is that two types of fermentation happen simultaneously. Lactic acid bacteria convert the milk’s lactose into lactic acid, giving kumiss its sour tang. At the same time, yeasts convert some of the sugar into ethanol and carbon dioxide, producing a mild alcohol content and natural carbonation. The result is something closer to a sparkling, slightly boozy yogurt drink than to beer or wine. Typical kumiss contains roughly 0.5% to 2.5% alcohol by volume, though stronger versions can reach higher levels depending on fermentation time.
What’s in the Fermentation Culture
The microbial community in kumiss is surprisingly complex. Research profiling kumiss samples has identified a diverse mix of bacteria and yeasts working together. The dominant bacteria include several species of lactobacillus (the same family of microbes found in yogurt and sourdough) alongside species of lactococcus. Acetic acid bacteria, the same type responsible for turning wine into vinegar, also show up and contribute to the drink’s sharp, acidic flavor.
On the yeast side, multiple species are present, with some of the same types found in kefir and other traditional fermented drinks. This dual fermentation, bacteria and yeast working in tandem, is the defining feature that sets kumiss apart from simpler fermented milks like yogurt, which rely on bacteria alone.
Why Mare’s Milk Matters
Kumiss is traditionally made from mare’s milk for a reason beyond cultural preference. Mare’s milk has a different composition than cow’s milk: it contains less casein (the protein that forms curds) and less fat. This means it ferments into a thinner, more drinkable liquid rather than thickening into something like yogurt. The higher lactose content of mare’s milk also gives the yeasts more sugar to work with, which is what produces the alcohol and fizz.
Some modern producers make kumiss-style drinks from cow’s milk, but achieving the right texture and flavor requires adjusting the milk’s composition, typically by adding whey or extra sugar to mimic the protein and lactose ratios of mare’s milk. Purists in Central Asia generally consider these versions a different product entirely.
How Kumiss Compares to Kefir
Kumiss and kefir are the two best-known fermented milk drinks that involve both bacteria and yeast, and they’re easy to confuse. The key differences come down to the milk source and the texture. Kefir is almost always made from cow’s milk (or goat’s milk) and is fermented using kefir grains, a rubbery cluster of microbes held together by a specific polysaccharide. Kumiss uses mare’s milk and a liquid starter culture rather than grains.
In practice, kefir is thicker, creamier, and only mildly alcoholic (often less than 0.5%). Kumiss is thinner, more effervescent, and noticeably more alcoholic. Both are sour, but kumiss tends to have a sharper, more wine-like acidity. Both are consumed widely in Central Asia and Eastern Europe, though kefir has become far more available in Western grocery stores.
The 19th-Century “Kumiss Cure”
Kumiss had a surprising moment in European medical history. In the late 1800s, a treatment known as the “climate-kumys cure” became popular in Russia for tuberculosis patients. The idea combined two elements: the supposed healing properties of the steppe environment (fresh aromatic air, abundant sunshine, open grasslands) with daily consumption of large quantities of kumiss. Sanatoriums sprang up across the Russian steppes, and George L. Carrick published a book in London in 1881 promoting kumiss for “pulmonary consumption and other wasting diseases.”
The treatment was popular enough that Baedeker’s 1914 travel guide to Russia still listed the most famous kumiss establishments. While the “cure” didn’t actually treat tuberculosis, it likely did help malnourished patients gain weight and strength. The fresh air and rest probably didn’t hurt either. The episode reshaped how Russians viewed the steppes, transforming their image from barren wastelands into curative landscapes.
Taste and How It’s Consumed
If you’ve never tried kumiss, expect something unfamiliar. It’s thin and watery compared to any cow’s milk product, with a sharp sourness, mild fizziness, and a faint alcoholic warmth. The flavor sits somewhere between plain kefir and dry sparkling cider, with a distinctly “horsey” or grassy undertone that reflects its source. Fresh kumiss is best consumed cold and doesn’t keep long without refrigeration, which is one reason it has never traveled far from the regions where it’s produced.
In Mongolia and Kazakhstan, kumiss is served to guests as a sign of hospitality. During summer months, when mares are lactating, production ramps up and kumiss becomes a dietary staple, sometimes consumed in quantities of several liters per day. Festivals celebrating the drink are common across Central Asia, and in Kyrgyzstan it is considered something of a national beverage.