Their are basically two groups of local natives. The first is less advanced and highly tribal. Some tribes play nice and others are just as likely to eat you as trade with you. The other culture has a smaller population but is more advanced, having developed masonry and basic metal working, and are generally accepting (if not a bit naive about the intentions) of the cities inhabitants.

I'm sticking to a "strangers in a strange land" theme with a vaguely european culture building a thriving city on the perimeter of a rain forest on a tropical continent. I'm borrowing heavily from similar situations in history, including the crusades, the discovery of the new world, the wild west, and numerous examples of the british empire throughout africa and the near east. My natives will be influenced by the cultures of the natives in most of those examples.

Most of the trade I'm talking about happens between those more advanced but distant cultures to either side. The city is just a convenient gateway to both or, more often than not, a neutral center that lets both sides come half way. Local products have a market too though. Those 'old world' crops that can grow in the harsh 'new world' environment (and wouldn't otherwise survive the trip) have found a market. New world crops that can be grown right outside the city have to travel less distance and are that much easier to get to market. The primitive locals cash in on locally grown spices, though plantations are becoming more common and cutting out the locals.


I think I'm comfortable saying that most of the other cultures accept, despite their greed, that the current situation is profitable and best left alone. The mad man who just doesn't care? Sounds like a campaign story arc to me, and is sort of the reason I developed the idea. With no formal army it falls to mercenaries, including the heroes of my campaign, to sort things out before things escalate to a seige.