Europe's oldest known town was a salt mine feeding the Balkans
Solnitsata in Bulgaria, now thought to be Europe's earliest town, was supplying the Balkans with salt around 5400 BC. For thousands of years this humble crystal preserved meat, sealed sacred agreements and served as money. Today, though, only a small share of the world's salt ends up in food.
Chemically salt is mostly sodium chloride, found as the mineral halite or refined into table salt. It supplies sodium and chlorine, which bodies need, and saltiness is one of the basic tastes. People who live off herds get enough from meat, blood and milk, but farming peoples eating mainly grain and vegetables must add it, which is one reason salt became a staple of trade as agriculture spread.
The oldest processing yet found is at Poiana Slatinei in Romania, where Neolithic people of the Precucuteni culture boiled spring brine to extract salt as early as 6050 BC; a Chinese salt works dates to roughly the same era. Egyptians placed salt and salted birds in third-millennium tombs, and from about 2800 BC swapped salt fish with the Phoenicians for cedar, glass and Tyrian purple dye. Herodotus described trade routes across Libya, and early imperial Rome built roads to haul salt from Ostia.
South of the Sahara it worked as currency; in Abyssinia slabs of rock salt served as coins. Tuareg Azalai caravans still travel from southern Niger to Bilma, each camel heading north with fodder and goods and returning with salt pillars and dates, though trucks now carry much of the load. Salt also carried meaning: Hebrews spoke of a covenant of salt, and victors sometimes scattered it on conquered ground. The famous tale of Rome salting Carthage in 146 BC is now thought to be invented.
Of roughly 300 million tonnes produced each year, most feeds the chemical industry, making chlorine, caustic soda, PVC and paper pulp, with more used on icy roads. Table salt is often iodised to prevent deficiency. Too much salt raises the risk of hypertension, and the World Health Organization advises adults to stay under 5 grams a day.
Source: Salt
