The Tale of Sovius, which forms the basis of the 18th chapter of the Chronograph of 1262, raises questions about its own origin - oral or translated-written. In East Slavic folklore we can find text comparable to the Tale of Sovius.
It is attested in the 12th century annals "The Tale of Bygone Years" (945-946), but it derives from an older collection of annals (Nachal'nyi Svod) dating back to the ninth decade of the 11th century. This collection is made of elementary folklore storylines traditionally called "Duchess Olga's Revenge on Drevlians for Her Husband's Murder."