I'm not an expert, but I think it's a given that high-value durable goods like this could change hands many times. For example, probably no-one travelled all the way with the Indian metal objects which have been found in Britain: https://www.caitlingreen.org/2014/12/indian-silver-coins-in-... .

This over-land route was common, afaik. It may be one of the reasons the Greeks founded a colony near the Rhone delta: present day Marseille.

Avoiding this route to sail directly to Northern Europe may also be why a Greek explorer from Marseille, Pytheas [1], gave us one of the first, if not the first, direct accounts of the British Isles.

[1] https://en.wikipedia.org/wiki/Pytheas

And Pytheas describes exactly how the tin got to the Mediterranean, at least in the 4th century BC.

The Amber Road is also a possibility:

From at least the 16th century BC, amber was moved from Northern Europe to the Mediterranean area.[2][3] The breast ornament of the Egyptian pharaoh Tutankhamen (c. 1333–1324 BC) contains large Baltic amber beads.

https://en.wikipedia.org/wiki/Amber_Road

Using the amber road would be quite a detour here, I imagine. That would mean that instead of crossing the channel and traveling through France and Italy, or circumnavigating the Iberian peninsula, you think it's more likely the tin traveled from Britain, across Scandinavia, then to the Baltics, and from there southwards across Eastern Europe?

Not that I have any knowledge of ancient trade routes, but to me having a trade route from Britain towards the northeast instead of southeast feels weird.

Yeah, I don't know much about the actual trade routes, I was more pointing out that 'stuff from northern Europe' made it to Israel / the Levant.

In any case, I don't think it's much more of a detour though, especially if we assume that it wasn't a specific journey, but a chain of multiple cultures interacting with each other. It doesn't seem implausible to me that tin went from Britain to Scandinavia then down the Amber Road, but I'm not a historian.

I assume "trade routes" are emergent things.

As in: Nobody decided "let's start a trade route from Egypt to Scandinavia!".

Far more likely, people traded with their neighbors, and market forces led to goods step by step traveling to where they were most valued.

Probably without Egyptians and Scandinavians ever having a clue the other group existed.

I buy tin in one market town and sell it for 5% more at the market town a week's journey away. Or I load up my ship with tin in one port town and sell it for 20% more at the port town a month's journey away. That tin can go quite a distance without any one captain having to load up in Penzance and do a long haul all the way to the terminal end of the Mediterranean.

But even that would have been possible, if anyone had enough knowledge of enough prices for common trade goods at enough of the ports along the way. One trip would make the owner, captain, and crew rich enough for it to be worth the risk.

Possible, but given the prominence of naval trade within the Mediterranean they might have been the ones running the northwestern hops as well.