The people in the slightly lower levels still know the people September was talking to last time - there's trade routes, as best as anyone can manage, and the groups try to keep in some level of contact, even if most groups don't get really big. There's a 'city' about forty miles that-a-way someone describes to them, on the same level - mostly a really big loose association of people staying near each other to trade a lot, which probably doesn't even top 'small village' sizes, but it's huge as far as local groups go. This group has a shelf witch near them who does technology - which isn't as tricky to read out as medicine, but still can be pretty tricky - so they've got a lot of things like motorized scooters.
They trade with a group from deeper down, too, sometimes - some of the weird stuff in the depths stays weird even if you bring it up, and that can be really useful. 'Weird' is mostly 'really magical,' as far as trade goods go - they have glowing stones that never stop glowing, and someone blind got a ring that lets them magically know what's right around them even if it's not exactly sight. Magical stuff's expensive, though - that stuff's heirloom goods, pretty much, and they had to trade a lot for it. Mostly good quality provisions books.
They help September fill out a bit of a vague guess map, at least as things were last time they heard from a trader. The map goes out past Rescue's hearing range.