Last time, it was a wilderness (well, city) encounter with some spectres. This time, we'll head back to Moldvay's Level 1 wandering monsters and #19 on the chart: Traders (B43).
I know it sounds weird, but bear with me here.
Traders in BX are different than merchants. They are "first level fighters who make their living trading goods." the listing goes on to say they are "similar to merchants, but much braver." They normally wield swords or hand axes, wear furs that count as leather armor, and carry shields.
Axes, furs, shields... hmm, what does that sound like?
VIKINGS, of course!
The vikings, in addition to the exploring and raiding, were terrific merchants and traders. They sailed all over, and were in a near-ideal position for commerce.
So, back to the encounter. Number appearing is 1d8. I rolled a 4. That's a decent party size for some NPCs but these are all fighting types with no clerics or wizards or thieves, so it makes sense they are a level 1 encounter. Not because they're wimps, but because they probably wouldn't venture far into the dungeon.
The listing in the book says they use pack mules in the wilderness, and typically carry trade goos like spices or furs or "carved decorative items." But these fellas are in the dungeon, so maybe the animals are back on the surface?
Traders have a low morale score (7), so they aren't interested in lots of fighting. They are probably in the dungeon looking for something valuable they can grab and go. Maybe they're hoping for some bits of jewelry or they've tracked an animal with a valuable pelt to its lair. In any case, they probably aren't "residents" of the dungeon. Like the PCs, they're just visiting.
I would see an encounter with this group as being far more likely to result in roleplaying than combat. A trading party might buy some loot off the PCs. The party might gain useful information from the traders about the place or the surrounding region (they're probably well-traveled after all). For the right price, the traders might even join the party for a bit and bolster their ranks.
In my scenario, I place the traders on the first level of the dungeon, relatively near the entrance. They have tracked some Giant Killer Bees (another level 1 monster) to this location and are searching for the hive. They are carrying green wood and lamp oil to smoke the insects out so they can steal the magical honey. The traders' reaction roll was a 9 (no attack, leaves or considers offers) which seems fair for mercantile types. If the party seems tough, the less than foolhardy traders might offer a trade: If the PCs can bring them a full jar of honey, the traders have a treasure map that the party might find worthwhile.
Like the NPC party, traders also serve as a reminder that the dungeon can be a dynamic, living place where the heroes aren't necessarily the only people interested in treasure; and sometimes even a dungeon encounter doesn't have to end up with rolling for initiative.