Airag is fermented mare's milk, lightly fizzy, faintly sour, and at the centre of Mongolian summer hospitality. We unpack the 3,000-year backstory, how a working family stirs a leather bag five thousand times a day, and how to accept your first bowl without giving offence.
Tsetsegmaa Dorj
Airag is fermented mare's milk. It is slightly fizzy, lightly sour, and roughly 1 to 3 per cent alcohol by volume. Mongolians have drunk it on the steppe for at least three millennia. In the countryside it is poured before guests sit down. In the city it is sold in plastic bottles at petrol stations from late June to early September. Mongolians count it as a "white food", or tsagaan idee, the sacred category that also includes butter, curd, and dried yoghurt.
Bronze Age burial complexes in central Mongolia have yielded traces of fermented dairy. The Greek historian Herodotus described a similar drink among the Scythians around 430 BC. The Secret History of the Mongols, written in 1240, mentions airag at almost every feast. The drink also shaped diplomacy. Marco Polo's account from the 1270s describes Kublai Khan's herd of 10,000 white mares, whose milk was reserved for the imperial family. Soviet collectivisation in the 1930s very nearly broke the chain. What survives today is largely the work of families who hid mares from registration and quietly kept their starter cultures alive.
The process begins with raw, unpasteurised mare's milk poured into a khokhuur, a smoked cowhide bag hung beside the ger door. The fermentation starter, called khurnug, is a portion of yesterday's airag. Each member of the family stirs the bag with a wooden plunger as they walk past. A fresh batch is churned between 1,000 and 5,000 times in a single day. After 24 to 72 hours, the lactose has converted to lactic acid and ethanol. The finished drink is white, foamy, and faintly scented of horse and woodsmoke.
Three provinces produce most of the country's airag. Arkhangai, where the rivers run clear, is known for the lightest bodied version. Ovorkhangai, around the old capital of Karakorum, ferments it longer and stronger. Tov, an hour west of Ulaanbaatar, supplies most of the airag served in restaurants. Senior guide Munkhbayar prefers the airag of Khujirt sum in Ovorkhangai. He drives the extra two hours to collect ten litres each summer for our guests.
Mares foal in late May. Milking begins in the second week of June and ends in early September, when the mares are dried off for winter. A working mare is milked 6 or 7 times a day, yielding only 250 ml each session. A family of four may keep 30 mares for airag and still count as a modest producer.
First sip: cold, sour, the foam settling on the upper lip. Second sip: a yeast note close to a young farmhouse cider. Third sip: the funk of the leather bag. New drinkers often compare it to kefir crossed with a rough white wine. Strength varies sharply by household. Two ferments from neighbouring families can read as different drinks, one tart and gentle, the other punishing. Most guests find the second bowl easier than the first.
Receive the bowl with the right hand, supported beneath by the left. Bring it to your lips and sip rather than gulp. If you cannot finish, touch your forehead to the rim and return the bowl. Refusing entirely is acceptable for guests with dairy allergies, but say so before the bowl arrives. A measured 100 ml is enough to honour the offer without unsettling an unaccustomed gut.
Our June through August itineraries pass through airag country by design. On the Khangai 7-Day Horse Trek, guests stop at three families and taste three ferments side by side. On the Karakorum Cultural Loop, guide Tsetsegmaa walks you through the khokhuur process before serving you a bowl. We also keep first doses small. Ten years of hosting have taught us that ambitious sampling on day one usually ends the day early.