I'm working in a low-fantasy setting of roughly mid-Renaissance development. Basically Earth-like with some mildly out-there plants and animals, but nothing overtly magical. I see a lot of questions about how huge cities work under these conditions and how big they can get, but not much information about midsize ones.
The specific setting is a smallish city run by an oligarchy of rich tradesmen/guilders. It has a lot of mines and its primary industries are related: iron working, silver working, etc.; it imports most of its food in return for these products. It has a supply of water along a good-sized river. The climate is on the cold side of temperate; to the south (this is in the southern hemisphere) there are some serious mountains that get very inhospitable, but it's not that bad where the town is located.
Historically, it was never a major administrative center like a provincial capital; it also doesn't have any religious/cultural significance (yet). It's connected to a very important trade route (where all the weapons and jewelry and such go) but it isn't a hub - there's basically nothing south of it.
Essentially, it's important in its region, but not in terms of the wider world.
So the question is twofold - how many people would live in and around the city (or town or whatever), and how many soldiers could it raise for long-term campaigning? I know there's a lot of factors that go into something like this, so an order-of-magnitude estimate is fine. I mostly just want to know if I'm going to end up with the kind of army where fifty or a hundred guys is a noteworthy force, or if I need to start drawing up regimental heraldry.