I found a "Russian bogatyrs" book that my grandma bought for my mom, and it has become a family book. However, there is one issue. The entire story takes place in Ukraine. And the very first sentence reads, "On high hills, there is a city of Kyiv"... Those are Kyivan Rus fairytales about mighty heroes, sort of Avengers of the 10th century. Moscow is not mentioned as it doesn’t yet exist.