This Brit has always thought that Shenandoah is not a shanty but a forebitter, that is, a song sung below decks by off-duty seamen. I have also believed that it originated among the trappers and fur traders of 18th/19th century North America and was taken up by the sailors whose ships carried the furs onward to Europe.

I think it's a good story and a beautiful song in the right hands.

Alan