It goes back to a Latin word that originally denoted an ‘allowance given to Roman soldiers for buying salt’ (salt being in former times a valued commodity, over which wars were fought, rather than taken for granted as it is today). This was salarium, a derivative of sal ‘salt.’ It soon broadened out to mean ‘fixed periodic payment for work done,’ and passed in this sense via Old French salaire and then Anglo-Norman salarie into English.
From Oecolampidius’s link. What wars were fought over salt? Salt would have been a valued commodity in inland areas, but as Dr.T suggests in the earlier thread, anybody along any coast could have derived salt at any time, unless it was illegal. As an aside, the word marinate seems to indicate it was normal practice to soak food in saltwater.
Here’s another question: salt is necessary to sustain life, but was it used mainly to enhance flavor or is it impossible to derive enough salt from a standard diet without supplement?
For example, selenium is also necessary for the body, but in parts of northern California the soil is deficient in selenium whereas in southern California there is an excess thereof. Hay and alfalfa grown in respective regions reflect either the surplus or deficiency so farmers have to be careful to balance fodder from both regions. (Or so I’m told.) Livestock can die from selenium depletion or excess. Civilizations such as Mesopotamia are thought to have perished because of a buildup of selenium due to irrigation practices (i.e. too much selenium) entailing insufficient drainage and leaching of the soil.
It seems unlikely that 5,000 or more years ago the inhabitants of the vast reaches of the inland continents depended on a salt trade for their existence.