D&D 5E Bush telegraph of EVIL

[tardigrade]

In my campaign the PCs are searching for a group of missing villagers. The villagers have actually entered some local caves and been captured by a tribe of evil humanoids who have just moved into the area and are going to try to auction them as slaves. However, I'm struggling to think of a mechanism for them to have alerted regional evildoers to the auction. Any ideas? The humanoids have a low-level spellcaster and I'm not averse to giving them some sort of fairly low powered magic item, but the move to the area was unplanned (they got kicked out of their old site by the Big Bad) so I want it to seem like something improvised rather than carefully planned.

Tl;dr - your tribe of evil humanoids is new to the area and holding an improptu slave auction: how do you get word out?

 

[Sunseeker]

Some kind of message runners more than likely, sent to areas where slaving is legal or at least in demand but kept on the down-low.

The spell Message/Sending?

 

[Satyrn]

Messenger pigeons they brought along with them specifically so they could contact their guy they left behind before coming to this place.

Wait, that sounds too organized.

One of the 3 messenger pigeons they managed to grab before fleeing, and they send a message to their guy they hope is still alive back there.

 

[Ancalagon]

Smoke signals, heliographs, animal messengers...

Sent from my [device_name] using EN World mobile app

 

[Kurotowa]

The humanoids have a low-level spellcaster

The spell Animal Messenger is exactly what you want for this situation. It's a second level spell, delivers a 25-word message for you, and it's a ritual so limited spell slots aren't an issue.