How Kosher, Halal and Jain diets signalled trust, turning food laws into passports for global trade

Have you ever been curious as to why Jews keep Kosher, Muslims keep Halal, or why Hindu and Jain Banias are strictly vegetarian? All these are trading communities. All have, for centuries, used food practices to establish a network of trust in global trade.

Long before the institution of insurance and credit control systems, faith in trading was built upon food. From Jewish traders in the Mediterranean to Muslim traders in the Indian Ocean, and Jain and Marwari traders in India, food restrictions were an important part of the architecture of trust among traders who never crossed paths.

The same predicament united traders on faraway shores, despite their differences and disparate conditions. Each trader would hand over goods or capital to a person located on distant shores, with a limited or no chance of ever travelling there. How could they be sure the recipient would not abscond with the money? A state contract was of no use on faraway shores, but a way of eating was transportable. Dietary law functioned as a signalling mechanism because it was costly to fake. Its uniqueness lies in the fact that while many can claim to be honest, few will actually uphold a lifetime of dietary restrictions, fasting schedules and rituals of food preparation for a deception.


As a Jewish trader sat down to eat in Cairo or Fustat in the 12th century alongside other Jews, he was not simply practising religion in the privacy of his own domain; he was marketing himself. Anyone looking would understand that this man was a member of a certain community, was known to that community's networks in other locations, and would negatively impact his standing, including his marriage and the well-being of his children, if he transgressed that community's law of trade. Historians of the Cairo Geniza have shown that Jewish Maghribi traders developed reputation systems spanning the entire Mediterranean. It is documented that news of a cheater in Alexandria would reach Tunis within a week, and a man would be completely cut off from trade.

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Similar logic applies to Muslim trade networks spanning from Arabia to Malabar to East Africa. Islamic commercial law enabled merchants to have a common code of contract and partnership law that operated in any port with a mosque. The mosque, along with the prescribed times of prayer and Halal practice, were part of the infrastructure of commerce. A merchant in a different port could enter the mosque and determine who kept the fast and correctly observed it, thereby locating people bound by the same law. This mechanism enabled Hadhrami and Gujarati Muslim merchant families to construct trading empires that continued to exist long after any single ruler or port city.

Jain and Marwari merchants in India created, perhaps, the strongest iteration of this framework. Their strict vegetarianism and avoidance of root vegetables, along with very specific fasting periods, made it very difficult, almost impossible, to fake over a lifetime. Since these were also predominantly endogamous trading castes, discipline in both food and marriage cemented each other. A Jain merchant from Rajasthan sent to a distant trading post had a set of habits that any other Jain merchant could authenticate, and that substituted for a credit check a stranger would never be able to conduct.

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All three cases demonstrate conversions from ritual to economic infrastructure. Food laws are difficult to forge, are evident in daily routines and are enforced by an entire community as opposed to a single court or ruler. This enabled people to identify and organise networks of trust with individuals to whom they could extend credit. They were able to punish members of their new networks for infractions of trust by excluding them from the network, regardless of where the infraction occurred.

It is important to note that none of these practices were initially devised as trade tools. They all had a logical framework and a moral origin: Jainism has compassion, Judaism has covenant and Islam has submission to divine law. What trade added to these systems was the recognition that these costly and visible systems could act as a passport and a credit reference. Trade did not form the basis of the systems; it added to their purpose.