Salt has been used for thousands of years by humans for dietary needs and food preservation. When salt was discovered to help with food preservation, lives were changed because foods that were only available seasonally were now able to be saved and eaten year round. Foods were also able to be preserved long enough to ship overseas, increasing the amount of trade in the food industry.
Civilizations have been built and founded around the location and availability of salts which also determined the power of the city. With how much of a commodity and desirable source salt was in olden times, empires were destroyed by war as others tried to obtain it.