Salt
People often traded salt for other things. It was of high value in China, Turkey, the Middle East, and Africa. In the Mediterranean area, including Ancient Rome, salt was even used for money. The word salary comes from the Latin word for salt, because they paid people in salt. After people learned how to get salt from the ocean, salt became cheaper. The Phoenicians were some of the first to figure out how to do this, by pouring seawater on dry land. Then when it dried, they collected the salt and sold it.