Given that goods typically moved by water (far less energy than overland), possibilities of longer voyages are somewhat more credible.

I don't know the actual history / archaeology, or quantities involved.

Europe does have a remarkably good inland navigable river network.

There's mention here that Scandinavians raided Mediterranian coastal towns and villages:

https://www.realmofhistory.com/2016/05/17/cypriot-copper-axe...

This map suggests a possible eastern route (the accompanying web page makes no mention of Sweden, scandinavia, or the Baltics):

http://theancientneareast.com/wp-content/uploads/2014/08/Tra...

(from: http://theancientneareast.com/the-bronze-age-world-system/)

Travel along the Donau, Dneiper, or Don rivers could have reached the Black Sea:

https://www.worldatlas.com/webimage/countrys/euriv.gif

This article and map suggest sea routes, through the Straits of Gibraltar:

https://www.speroforum.com/a/ROURBRXIJL49/77965-Ancient-trad...

Re: more likely, each was traded a dozen times...the goods reached people the manufacturer had no idea existed.

Some things never change: https://www.steelavailable.com/en/counterfeit-steel-big-worr...

Transaction costs limit how many people are in these chains. It’s far more common for individual merchants to be paying taxes to several groups vs large numbers of groups being involved in the trading.