A human space civilization once established a colony on a planet. Now, several centuries later, the people on this planet are only at a medieval level of technology. Whether by accident or on purpose, I have yet to consider. The former beliefs, form of government, and borders of the space civilization may have changed in the meantime.
About once a year a ship of the space civilization lands on the planet unnoticed. They disguise themselves as local traders and trade with the inhabitants for a good price. The traders pay more than one would normally get. As a result, they are considered friendly and generous and are welcomed. They do this for at least a few decades, maybe longer.
The traders do not help the locals to advance technologically themselves. They do not completely hide the fact that they are technologically superior, but they do not teach the locals any technological advances. For example, they might trade slightly superior non-electronic tools, but would never use or trade electronics or projectile weapons.
The story takes place from the point of view of the medieval civilization. There, the traders always travel to the same city. It is possible that there are similar cities further away that are also visited by traders.
My question is now, why would they trade at all? What would be their long-term goal?
If you can mine or breed the resource, why not industrialize the mining or breeding? You could give the locals (your own species in the end) better knowledge and tools or use your own workers. The same goes for the manufacturing of goods, which could be industrialized. Living beings can additionally be bred on other planets. Knowledge can also be copied and used elsewhere.
My ideas so far:
- This passage could work well as a later plot twist. I guess usually the first thought would be the resource is valuable and therefore traded. The traders might have a hidden agenda that is discovered only much later in the story.
- It's not about the goods they bought, but the ones they sold that they leave behind.
- Political reasons between two space powers (trade agreements, espionage, conservation).
- The bought/sold goods are illegal or the deposit must be kept secret.
- They are not concerned with trade, but with low-key interaction with the local population for some reason.
- By extracting or producing the resource, another side process takes place. The actual goal is to promote that process. But then why not industrialize the process directly?
Unfortunately, I'm having a hard time finding concrete examples for the different approaches right now, or further reasons for the behavior of the traders.