Tyranny of Dragons
Cult of the Dragon
The Cult of the Dragon is behind the attack on Greenest, though at this point no-one really knows why, how many there are, or their future plans.
They had a camp nearby where they mustered cultists and mercenaries to attack and loot nearby towns. The camp included a cave system where Rezmir was attempting to hatch three black dragon eggs. The eggs were smashed by the party.
The riches stolen by the cult have been sent north along the Trade Way, hidden as part of a regular merchant caravan.