Yahang brokers vouched for China's unknown buyers

Long-distance and wholesale trade in imperial China ran into the same problem in every new market a traveling merchant entered: a trader arriving with a boatload of grain, indigo or cloth had no way to know which of the dozens of small local shopkeepers wanting to buy on credit would actually pay, and a shopkeeper had no credit history a stranger from another province could check. Refusing to extend any credit at all would have collapsed most wholesale trade, since few small retailers held enough cash to buy inventory outright.

China's markets solved this with 牙行 (yahang), brokers who had existed informally since the Han dynasty but were most fully regulated from the Ming dynasty onward. Rather than leave merchants to individually vet unknown retailers, the government required brokers to be, in the legal code's words, propertied and reputable people ('殷实良民'), backed by mutual-guarantee bonds from other licensed brokers, and formally licensed through a permit system ('牙帖') that tied a broker's ability to keep operating to his own conduct.

Shifted credit risk to the broker, whose licensed standing the government could revoke, so he had incentive to vet which local buyers he backed.

Broker's own money and license at risk made him vet buyers carefully.

Merchant extended credit to broker's standing, not unknown shopkeeper.

Government licensing and mutual bonds kept brokers accountable and reputable.

Concentrating trust in few brokers made vetting scalable for wholesale trade.

When you can't vet every small counterparty, concentrate trust in a few accountable intermediaries who stake their own capital and reputation on the people they vouch for.

The yahang system remained the dominant form of market intermediation across China for centuries, still heavily used well into the Qing dynasty, handling everything from small livestock and grain markets to major regional trades like the indigo trade through brokers in cities such as Changsha and Xiangtan.