Trade is central to every key economic issue we face. Whether the subject is inequality, financial instability or the future of work, it all comes down to a discussion of trade: trade of manufactured goods with China, trade of bonds with Europe, trade over the Internet or enabled by mobile apps. For decades, economists have sought to understand how trade works. Can we shape trade to achieve different outcomes, like a resurgence of manufacturing or a lessening of inequality? Or does trade operate according to fairly fixed rules, making it resistant to conscious planning?

Economists, creating models of trade, have faced a challenge, because their data have derived exclusively from the modern world. Are their models universal or merely reflections of our time? It’s a crucial question, because many in our country would like to change our trading system to protect American jobs and to improve working conditions here and abroad. The archives of Kanesh have proved to be the greatest single source of information about trade from an entirely premodern milieu.

In a beautifully detailed new book — ‘‘Ancient Kanesh,’’ written by a scholar of the archive, Mogens Trolle Larsen, to be published by Cambridge University Press later this year — we meet dozens of the traders of Kanesh and their relatives back home in Assur. Larsen has been able to construct family trees, detailing how siblings and cousins, parents and spouses, traded with one another and often worked against one another. We meet struggling businessmen, like Assur-idi, and brilliant entrepreneurs, like Shalim-Assur, who built a wealthy dynasty that lasted generations. In 2003, while covering the war in Iraq, I traveled to many ancient archaeological sites; the huge burial mounds, the carvings celebrating kings as relatives to the gods, all gave the impression of a despotic land in which a tiny handful of aristocrats and priests enjoyed dictatorial control. But the Kanesh documents show that at least some citizens had enormous power over their own livelihoods, achieving wealth and power through their own entrepreneurial endeavors.

The details of daily life are amazing, but another scholar, Gojko Barjamovic, of Harvard, realized that the archive also offered insight into something potentially more compelling. Many of the texts enumerate specific business details: the price of goods purchased and sold, the interest rate on debt, the costs of transporting goods and the various taxes in the many city-states that the donkey caravans passed on the long journey from Assur to Kanesh. Like most people who have studied Kanesh, Barjamovic is an Assyriologist, an expert in ancient languages and culture. Earlier this year, he joined some economists, as well as some other Assyriologists and archaeologists, on a team that analyzed Kanesh’s financial statistics. The picture that emerged of economic life is staggeringly advanced. The traders of Kanesh used financial tools that were remarkably similar to checks, bonds and joint-stock companies. They had something like venture-capital firms that created diversified portfolios of risky trades. And they even had structured financial products: People would buy outstanding debt, sell it to others and use it as collateral to finance new businesses. The 30 years for which we have records appear to have been a time of remarkable financial innovation.

It’s impossible not to see parallels with our own recent past. Over the 30 years covered by the archive, we see an economy built on trade in actual goods — silver, tin, textiles — transform into an economy built on financial speculation, fueling a bubble that then pops. After the financial collapse, there is a period of incessant lawsuits, as a central government in Assur desperately tries to come up with new regulations and ways of holding wrongdoers accountable (though there never seems to be agreement on who the wrongdoers are, exactly). The entire trading system enters a deep recession lasting more than a decade. The traders eventually adopt simpler, more stringent rules, and trade grows again.