Airag is a mildly alcoholic fermented drink made from mare’s milk, and it is the national beverage of Mongolia. White in color with a tart, slightly fizzy taste, airag has been central to Mongolian nomadic life for centuries. It typically contains 1 to 3 percent alcohol and carries a pleasant sour smell often compared to kefir, though the flavor is distinctly its own.
How Airag Is Made
The process starts with fresh milk from mares, which is collected during the summer months when horses are actively nursing. Mare’s milk is thinner and sweeter than cow’s milk, with more lactose and less fat, which makes it especially well suited to fermentation.
Raw mare’s milk is poured into a large container, traditionally a cowhide sack called a khokhuur, and mixed with a small amount of previously fermented airag that acts as a starter culture. The mixture is then stirred repeatedly, sometimes hundreds or even thousands of times a day. This constant agitation introduces oxygen and keeps the fermentation even. Historically, the khokhuur would hang near the entrance of a ger (the Mongolian felt tent), and every person passing by would give it a stir.
Two types of microorganisms work together during fermentation. Lactic acid bacteria break down lactose into lactic acid, giving airag its sour tang and lowering the pH to around 3.5. Yeasts, meanwhile, convert sugars into small amounts of ethanol and carbon dioxide, which gives the drink a light effervescence. Research on airag from Inner Mongolia has identified several key players in this partnership. Certain lactic acid bacteria break lactose into simpler sugars like glucose and galactose, which non-lactose-fermenting yeasts can then use to produce alcohol. One yeast strain studied produced ethanol only when grown alongside bacteria, not on its own, highlighting how deeply these organisms depend on each other.
Fermentation takes roughly two to three days in warm weather. The finished product is a pourable, slightly thick liquid that’s mildly sour, faintly boozy, and a little fizzy.
Airag vs. Kumis
If you’ve come across the word “kumis” (also spelled koumiss or kumyz), it refers to the same basic product: fermented mare’s milk. The difference is regional. In Mongolia, the drink is called airag. Kumis is the term used across Central Asian Turkic-speaking countries like Kazakhstan, Kyrgyzstan, and parts of Russia. Production methods vary slightly from region to region, and the microbial cultures differ depending on local tradition and climate, but the core concept is identical.
Nutritional Profile
Airag is a nutrient-dense drink, particularly rich in minerals. Analysis of 51 samples found average concentrations of 722 mg/L of calcium, 432 mg/L of phosphorus, 428 mg/L of potassium, 114 mg/L of sodium, and 53 mg/L of magnesium. That calcium content is notable: a liter of airag delivers a similar amount to roughly two glasses of cow’s milk.
Because fermentation breaks down a significant portion of the lactose in mare’s milk, airag is easier to digest than fresh milk. This matters in Mongolia, where lactose intolerance is common. The lactic acid bacteria do much of the work, converting lactose into lactic acid before the drink ever reaches your stomach. Airag is also a source of B vitamins and vitamin C, the latter being unusually high in mare’s milk compared to cow’s milk. For nomadic herders who historically had limited access to fruits and vegetables, this made airag an important nutritional safeguard during long winters.
Cultural Role in Mongolia
Airag is far more than a casual drink. UNESCO inscribed the traditional technique of making airag in a khokhuur, along with its associated customs, on its Representative List of the Intangible Cultural Heritage of Humanity. Mongolia’s National Center for Cultural Heritage describes it as “one of the national prides of Mongolians,” particularly among nomadic herders who remain the primary keepers of the tradition.
The drink plays a role in daily hospitality, religious offerings, and ritual blessings. When guests arrive at a ger, they are offered a bowl of airag as a sign of welcome and respect. It is served at weddings, during Naadam (Mongolia’s largest annual festival featuring horse racing, wrestling, and archery), and at seasonal celebrations marking the start of the milking season. Airag also appears in spiritual contexts: it is sprinkled as an offering to the sky, the earth, and the four cardinal directions.
For herders, the airag season structures summer life. Mares are milked several times a day, and the rhythm of stirring and tending the fermenting milk becomes a communal activity that involves the entire family. Production peaks from June through October, and a healthy mare can produce enough milk for several liters of airag per day.
Traditional Health Uses
Mongolian traditional medicine has long considered airag therapeutic. It is regarded as easily digestible and is given to people recovering from illness. UNESCO’s documentation notes it “has been proven to be effective for curing certain diseases,” a claim rooted in centuries of traditional practice. In the 19th and early 20th centuries, kumis therapy (essentially prescribed courses of fermented mare’s milk) was practiced in Russian sanatoriums for patients with tuberculosis and other chronic conditions.
Modern interest in airag’s health properties centers on its probiotic content. The lactic acid bacteria that drive fermentation are closely related to strains used in commercial probiotic products. These bacteria can support gut health by competing with harmful microbes, aiding digestion, and potentially modulating the immune system. The combination of live cultures, reduced lactose, and high mineral content makes airag something like a naturally occurring functional food, long before that term existed.
What It Tastes Like
First-time drinkers often describe airag as an acquired taste. It’s sour, similar to plain yogurt or buttermilk, but thinner and with a slight carbonation that tickles the tongue. There’s a faint horse-milk muskiness underneath. The alcohol is barely perceptible at the lower end of the 1 to 3 percent range, roughly equivalent to a light beer, though some batches fermented longer or in warmer conditions can be more noticeably boozy. The Mongolian cultural heritage center describes it simply: “a delicious smell and its pleasant taste can make your mouth watery.”
If you visit Mongolia during summer, you’ll find airag served in nearly every ger and at roadside stands throughout the countryside. It is typically offered in a shared bowl and drunk at room temperature. Refusing a bowl outright is considered impolite; the custom is to take at least a small sip before setting it down.