As
@Iyapo noted, the rings will get more expensive as you continue out. However, with the exception of the orcs, they will never ask for a resource you haven’t unlocked yet. Once you unlock the next set of manufactories, provinces will start requiring those second tier goods, but not until then. However, you’ll very quickly run out of things you can do at all if you don’t unlock them, so it’s not advised to put it off for that reason.
(Also, I know scouting seems like a tempting way to unlock more space or gather kp, but it’s seriously advised for new players not to unlock more provinces than are required to get into the next chapter. You can see that number in your research tech tree. If you scout much farther than that, the costs will quickly become astronomical compared to what your city can produce, and many new cities have gotten themselves in a real pickle, being unable to take part in events and having to wait months for their cities to stabilize.)
Welcome to the game!
The
Wiki didn’t address this particular question, but does have much information and is suggested reading when you’re trying to learn about something new. The
Scrolls of Knowledge section here on the forum is also a good resource, consisting of collected links and player-contributed info sorted into categories.