I can't read russian, but I just clicked the first two samples hopping to see the photos of the letters. There are photos and a hand draw version to show the letters, so I'm not disapointed.

Each post has a Russian translation and two English translations, but the English translations are empty. Do you know why? (Why it is empty or why they added a button to show no info.) What is the Russian translation? (Is it a trasnlation fro old Russian to modern Russian?)

Is there a page with more info? Like: How they wrote it? Why they used bark instead of paper? How this samples survived?

A number of the exhibits do have an English translation but not most, looks like some of these documents are financial or legal.

The ones labeled in the right-hand column as "Фрагмент" are scant fragments, perhaps of once-larger pages, doesn't look like much translation effort was put into those.

There's some likelihood there were many locations where paper was extremely uncommon compared to conveniently peeling bark off of suitable trees.

As children, kids in my neighborhood were often peeling pages off of the local melaleuca trees which have a nice white bark in layers and writing on it with ball-point pens. Pretending to write messages in an imaginary ancient Native American or futuristic science-fiction environment.

Edit: I would also wonder how the ones from the 11th century were preserved as long as the 15th century to start with.

Which ones are the most interesting ones you found? (Can you pick 2 or 3?)

Only looked at about a dozen or two.

Seems like the ones having more descriptive cyrillic text but not fragments.

Greetings and homage to some nobles were there, with some monetary records and religious material.

Where some of these were made it's always possible there was only one literate person at the time for miles around. Might even represent generations of official recordkeeping which lucked out being preserved more reliably than personal "papers" might be.

OTOH some of these could be IOU's which would basically amount to a form of "paper" money. No printing, no pen, no ink, no paper! If so, individuals would probably hang on to them pretty tightly.

Also in illiterate situations there can be a lot of superstition about documents which are widely recognized as disproportionally important, because almost nobody can actually read them.