The local king / mayor

sure but what about inter-kingdom trade (and even, not all cities belonged to an empire)

You taxed and regulated at ports of entry

That's not a regulated market, you can sell elsewhere

If that's your criterion for what constitutes a regulated market, then there can be no such thing as a regulated market, because you can always sell elsewhere.

And defining a concept in a way that means it can't exist makes no sense, so that criterion can't reasonably define this concept. (Was that a reductio ad absurdum?)