Yakut people, like steppe nomads, used to make almost all koumiss utensils from “siri” leather, which was waterproof. It was used for sewing “siri kolloqos” — large vats, “kogyor” or “simiir” — leather bottles for cooking and transporting koumiss by pack transport, “simiircheh” — small leather bottles, “chabychakh” — flat bowls, milk pails and other items.

The abundance of leather vessels for koumiss indicates that the majority of Yakuts, who were engaged in horse breeding, were nomads. In the conditions of nomadic life, which was associated with frequent travel on horseback, durable and strong leather utensils were indispensable. Andrey Savvin, a local historian and folklorist wrote about it in his work “Yakut food before the development of agriculture”.

The process of making “siri” leather consisted of several stages. First, the frozen rawhide was spread on the ground and smoothed out with an iron scraper “kyhyakh”. Then the wool and excess layers were removed. After being melted, the skin was stretched on the frame in the form of one big plate with thin hair ropes through the holes that were made along the edges. Then it was smeared on both sides with the blood of domestic animals, which was mixed with a small amount of butter. After that, the material was smoked in a special room. The procedure of smudging and smoking was repeated several times, and in the intervals the leather was dried over a hearth, or a small fireplace, or in the sun. When the maker considered the material sufficiently impregnated with smoke, both sides were smeared with butter or horse fat.

Siri was considered thoroughly worked when it took on a black hue and became very dense.

In some places, for example, in the town of Verkhoyansk, the peeled rawhide was put for a long time in a dish with the blood of domestic animals. After being dried in a special room it was fumigated with smoke.

Before cutting, the siri was soaked in water. As a result of such treatment, the leather became waterproof. As a rule, it is used to sew utensils for koumiss and horse milk: “kholloqos’y”, “yaqas’y”, “chabychakh’y”, “simiyir’y”.

Andrey Savvin, the first director of the Churapchinsky Museum, described in detail the koumiss utensils of the Yakut people.