The NWC art forms began in prehistoric times, but on a very small scale. Excavations in sites produce carved shell and stone ornaments as well as some ornamented utilitarian items, which one might consider proto NWC art themes. We don't know about wood, but it seems reasonable that they carved it, as well.
There was small amount of native copper and meteoric iron, but that could not provide the means for the massive florescence of art forms that began in the very late 1700s.
Starting in the 1600s Mexico began maritime commerce with Asia and set up regular schedules for the ships setting out from Acapulco on the Japanese current.
On the return voyage the Manilla Galleon fleet sailed past some of the NW shores and occasionally a ship was wrecked. It seems that the locals did not take in survivors, but may have killed them. In one instance, downriver along the Columbia, a Spaniard, named Soto, convinced the Chinook to spare his life since he was a blacksmith and could work iron. This they apparently did and a village was pointed out to Lewis and Clark as the 'Shoto Village' where he had lived. No dates are given for his life.
The Spaniards sent the Malespina Expedition, (in the 1790s), to the NW to head off Russian and English incursons. It was too little too late, of course, but I would not be surprised if they had been active on a small scale in the area for some time, as it was territory of New Spain. The galleons were forbidden to land for any reason, by law, but it is almost certain that some did. So, some trade likely occurred on those occasions. Another source, however small. Just some additional thoughts on this subject.
If someone will email me an address, I will send the DVD of the horn to you and ask you to post the photos, as I work off of a piece of $#@* apple with more limitations than applications. I will copy the disc so that there will be no need to return it. Give me a few days, if you would.
Dick
