Although it was in use in China before the advent of the Mongols, the paiza, an inscribed metal plaque that functioned as a passport or a patent of office, became a symbol of Mongol administration used to regulate and secure communication in the vast empire.
Most paizi were circular or rectangular and were worn either fastened on an item of clothing or suspended from the neck to make them visible to customs officers. Marco Polo on his return journey to Venice would have carried one.
The paiza is made of iron with inlay of thick silver bands forming characters in the Phagspa script devised for the Mongol language in 1269 by the Tibetan monk Phagspa.
The inscription reads in translation (by Morris Rossabi):
By the strength of Eternal Heaven,
an edict of the Emperor [Khan].
He who has no respect shall be guilty.