though paper is an ancient invention (approx. 2nd century bce), it was not known in europe until approx. 11th century, and did not become somewhat ubiquitous until approx. 14th century.

when reading a fantasy story, i always try to place it somewhere on the technological timeline

in the world of «the silverblood promise» paper seems to be ubiquitous and the only writing medium, it is mentioned without reverence, as smth usual and abundant. so, technologically it's not earlier than 14th or 15th century.