http://mobile.nytimes.com/2014/10/19/world/europe/where-mud-is-archaeological-gold-russian-history-grew-on-trees.html?referrer=

etched?  Doesn't seem likely, and doesn't look like it in the photo.  Kashmir was a major source of birchbark at this period.  Could the Novgorod scrolls be on bark from Kashmir? 
Dominik Wujastyk, from Android phone.