In his 2002 book, Salt: A World History, author Mark Kurlansky delves into the history of salt, as well as its impact on empires, wars, and economies, in a text that is lively, comprehensive, and surprising. The book is divided into three parts and begins thousands of years in the past. Kurlansky traces the earliest knowledge of salt in the histories of China and Egypt. The Chinese made salt from evaporated seawater and used it to make sauces and sprinkle on food. The Egyptians used salt during the mummification process, and also added it to their food. As the Roman Empire swept across Europe, its armies required salt, both for the men and their horses, which led to a greater need for salt production.

Salt in the Middle Ages was a staple of Europe. Meat was the primary source of food—fish and beef. Because meat could not be eaten on fast days, of which there were many, the meat had to be preserved, which was accomplished by curing with salt.

The Gaul and Celt tribes were responsible for the drilling and excavation of primitive salt mines. When they were conquered by the Romans, Rome absorbed the salt apparatus that they had constructed, expanded them, and reaped the profits. Rome would not be responsible for innovating methods of salt production or refinement, but would expand the scale of the salt industry to a degree previously unknown.

After outlining the realities of the cod market in the 17th century, Kurlansky gives the history of salt in what would become America. Salt shortages, followed by a salt inequity, caused great deal of unrest in America. Combined with unjust taxation on salt and other commodities, this gave rise to the American Revolution. In Europe, a hated salt tax known as the gabelle was having a similar effect on rebellious elements who were tired of government oppression. Kurlansky charts the course of the French Revolution, which led to the overthrow of the French monarchy, and its relationship to salt.

In the next section of the book, India gains its independence from British rule after a long struggle that involves the peaceful demonstrations of Gandhi. Gandhi made the oppressive salt tax of the British Crown a symbol of his defiance, and encouraged his followers to do the same.

The final third of the book concerns the ways in which ancient economies founded on salt persist into modern day, and catalogs the inventions and innovations that have resulted as byproducts of producing salt, and searching for it.

The central question of Salt is how something that is often viewed as a simple ingredient could have had such influence on past societies, and how salt helped shape modern-day life. Kurlansky also invites the reader to ponder the question of why something as abundant as salt has been treated as if it were a precious, scarce resource. The empires he discusses were not formed by a search for gold, silver, or other precious commodities, but for salt, which was accessible to everyone.