Originally, this type of leather was tanned with willow bark or birch bark and greased with birch tar oil for waterproofing. The birch tea gives the leather its typical smoky smell (like smoked bacon).
Usually vegetable-tanned leather is not particularly waterproofed. But with birch tar oil, the water resistance can be achieved without greasing the leather excessively and without compromising the Breathability of leather. Shoes and boots from these leathers keep the feet extremely warm, at very low temperatures, and cool at warm outside temperatures.
In German-speaking countries, Russia leather is known as "Juchten Leder" or "Juften".