the "free" modifier is sort of meaningless but markets exist anywhere that things are traded repeatedly. If markets require a state, then what are black markets

the "free" modifier is sort of meaningless but markets exist anywhere that things are traded repeatedly. If markets require a state, then what are black markets? I forget what it's called, but there's a type of market where people belonging to different, warring societies find ways to negotiate and trade by using something like dead drops necessarily without ever meeting face to face. Edit, found it: https://en.wikipedia.org/wiki/Silent_trade https://en.wikipedia.org/wiki/Silent_trade