The History of Salt
Salt was in use long before recorded history. Since the dawn of time, animals have instinctively forged trails to natural salt sources to satisfy their need for salt.
Early human hunters obtained their salt from eating animal meat. As they turned to agriculture and the diet changed, they found that salt (maybe as sea water) gave vegetables the same salty flavour they were accustomed to with meat.
Over many millennia, they learned how salt helped to preserve food, cure hides and heal wounds. Nomadic bands would have carried salt with them and traded it with other bands for different goods.