I would have figured that it would have been primarily independent traders that handled most long distance trade, and that this wouldn't have been a particularly high volume trade good, so there would be a good chance that the fraction of records we've recovered don't contain any mention. I have very little education in this area, though. Thanks for all the info!
The concept of independent traders and a merchant class uncontrolled by a central palace system of government really didn’t emerge until after the Late Bronze Age collapse circa 1170’s BCE. Before that, it was all about central control through the sovereigns, their (hugely extended) families, a system of “gift exchanges” that look a lot like commerce to us today, and control through priesthoods. It just wasn’t an option to get up and be a merchant on an international scale without your god-king giving you the rights at that time.
