Mongol Empire made passports whose material was the entitlement

The Mongol Empire spanned a scale no previous empire had administered, with messengers, officials and merchants needing to move quickly across thousands of miles and dozens of local jurisdictions, each staffed by officials who had never met the traveler and had no way to check their identity or authority against any central register. A written letter of authorization was slow to verify, easy to forge or alter, and meant nothing to an illiterate relay-station keeper hundreds of miles from wherever it was issued.

What the empire needed was a credential that any official, anywhere, could recognize and trust instantly without reading anything or checking any record — and that also communicated, without any additional explanation, exactly what the bearer was owed: full escort and provisions for a top envoy, a fresh horse and a meal for an ordinary courier.

The Mongol khans issued paiza (gerege) tablets in a fixed material hierarchy — wood, bronze, silver and gold — where the tablet's own material, not any writing on it, signaled the bearer's rank and exactly what they were entitled to claim at relay stations along the yam network: lodging, food, fresh horses and escort scaled to the tablet's tier. A gold paiza, the highest tier, entitled its bearer to the empire's fullest support; the Venetian traveler Marco Polo is recorded as having carried a foot-long gold paiza issued personally by Kublai Khan.

Encoded the entitlement into the tablet's material — wood, bronze, silver, gold — so rank and claim were recognizable on sight, needing no reading or verification.

Material hierarchy made rank recognizable without literacy or central records.

Gold and silver were hard to forge, so the credential was naturally anti-counterfeit.

Instant recognition meant no delay or judgment call at relay stations.

Consistent tiers let officials know exactly what to provide, reducing disputes.

When verification is impossible at scale, encode the entitlement into the credential's own physical properties so it is self-evident and hard to fake.

The material-tiered tablet let officials across the empire, whatever their literacy or distance from the capital, recognize a bearer's authority and entitlement on sight, without needing to read, verify or contact anyone — obstructing a paiza-bearing courier or envoy was treated as a serious offense.