[crabbone]

Ukrainian tradition and folklore prominently features these guys: https://en.wikipedia.org/wiki/Chumak . While the Wiki page mentions that in Ukrainian The Milky Way is called The Way of Chumaks it doesn't explain why -- but if you know the folklore, you'd immediately see that the idea is that it's the salt spillovers from their carts.

Salt was one of the most important goods that were traded over long distances. And no, technologically it wasn't advantageous to transport seawater or try to convert seawater into salt. Ukrainian city of Soledar that was prominently featured in the news last year literally means "gifting salt" -- and it has huge historical salt mines under it.

So, not only in antiquity, all the way through to the 19th century salt was one of the key goods traded over long distances. It wasn't as scarce as diamonds, but due to high demand it was still a worthwhile thing to trade.