It's not an easy thing to mount a big exhibition of artifacts from China without any artifacts from China.

That’s the position the University of Pennsylvania Museum of Archaeology and Anthropology now finds itself in, as it prepares to open a major show on Saturday, “Secrets of the Silk Road,” which was organized by the Bowers Museum in Santa Ana, Calif., last year and traveled from there to the Houston Museum of Natural Science.

The Penn Museum, as it is known, had advertised its version of the show as “an extraordinary collection of materials, including spectacularly preserved clothing and textiles, personal items and golden treasures, all recently excavated at desert burial sites in the far western reaches of modern China.” But on Wednesday the museum announced that China had requested that none of the artifacts be shown. In a statement the museum said the exhibition “has been modified,” and will now consist only of photographs, multimedia presentations and a recreation of an excavation site. It added that it would refund money to everyone who had bought tickets for the show ahead of time and that the exhibition would now be free....