The original Yakutian kumis is stiff and is made of horse milk.
To make it yakuts used a tightly closed leather vessel — «simiir», which was made from the leather of an adult horse and they connect it with scrapings inside. The leather was cleaned from hair, smoked and oiled. There were some vessels from 16 to 48 liters and from 50 to 150 liters. Kumis, which was made inside of «simiir», differed with high taste qualities, had fizzy foamy consistency because of too much gas in it.