Quoting from a website entitled Russian Crafts:
The principle of making dolls remains unchanged until the present time, keeping all the tricks of turning skill of Russian craftsmen. Usually a turner uses such wooden materials as lime and birch. Timber that is intended for the manufacture of dolls, usually is cut down in early spring, purified from the bark, leaving in some places of the log rings of bark to prevent during drying cracking of the wood. Prepared in this way the logs are stacked in piles, between them there is a gap for air flow. Usually timber is kept in the open air for several years to bring it up to a certain condition, avoiding not proper drying. Only an experienced master can determine the readiness of the material. Ready to process the logs are sawn into billets for future dolls. The doll blank overcomes though up to 15 operations in the hands of a turner before becoming a finished doll.If you look closely you will see some of the dolls do not have "Russian" themes.