Where did chief joseph get a cuniform tablet?

Among the effects of Chief Joseph, the famed leader of the Nez Perce Indians, was a clay tablet bearing a cuneiform inscription. The tablet transmits no startling message, being merely a receipt for one lamb changing hands. But where did a Northwest Indian chief get a 3,000year-old tablet? The tablet first came to light around 1878, long before cuneiform tablets became common on the artifacts market. Still, it could have been a gift from some missionary or tourist -- or even planted as a hoax.

(Park, Edwards; "Where Did Chief Joseph Get a Cuneiform Tablet?" Smithsonian Magazine, 9:36, February 1979.)

Reference. For other enigmatic New World tablets and inscriptions, read our Handbook: Ancient Man, which is described at: here.