https://youtu.be/EZ2PS5S6w1c?si=SQPVTcSt9SZCSvrO
Standardized currency in the form of copper rings, thin ingots (which I can't help but think resemble boats), and ingots in the shape of axe heads. The sheer amount of these objects with no variation implies a civilization with an almost industrial output of this currency, and currency like this would only be needed by a significantly advanced, sophisticated, and large civilization.
The tendency upon recovering graves with goods is to assume the dead would carry the 'sacrificed' items into the afterlife. Obviously there is no reason for a Frya's people to have this tradition, so the idea of these goods being buried with someone of status in order to take the currency out of circulation and in-effect lower inflation seems attractive. It is also human tendency to be buried surrounded by belongings regardless of afterlife beliefs, as seen today with people being buried with watches and jewelry.