[Wytwwww]

> currency (a standardized medium of exchange)

That's a pretty recent innovation, standardized coins didn't appear until the 600s BC, barely 100-150 years or so prior to the Greco-Persian wars. Widescale international trade existed for 1000+ years prior to that as far as we know, you don't necessarily standardized money for that.

[ETH_start]

Large scale international trade relied on standardized forms of money for thousands of years before the first coins were minted:

https://www.pnas.org/doi/10.1073/pnas.2105873118

[ben_w]

I'm not sure why you're describing 600s BC as "recent"?

[Wytwwww]

Because we know that there were much older civilizations during the bronze age which relied on long distance international trade and at least their ruling classes were dependent on it for their survival.