re "ivory"
This caught my eye:
''and you will bestow what is better than all you can receive, whether quintals of fish, sands of gold, choicest fur or most beautiful ivory."
I think what must be being referred to are walrus tusks.....unless anyone may know if mammoths had yet been found in the Alaska permafrost, which may indeed be the case.  "Ivory" in either case could maybe used a footnote.