I was curious about how salt collection worked in very early civilization, particularly away from coastal areas. The earliest content I've heard about it was Mali and the early African salt/gold kingdoms, but I'm interested about how it was collected long before that. I'd imagine that for inland areas, salt mines would be the first excavated resource people mined from the Earth. What is the earliest historical evidence for salt collection, then how and where did the institutionalization of salt collection begin to form in early civilization? For general range I'm interested in is anything predating 900B.C.
Thanks for your time!