At first they suspected rival slave traders or mercenaries hired by the other cities to corner the market on the trade, but all the traders were being killed one caravan at a time.
The mercenaries were hired by other cities to help with trading slaves.
mnli hypothesis: The mercenaries were hired by other cities to help with trading slaves. premise: At first they suspected rival slave traders or mercenaries hired by the other cities to corner the market on the trade, but all the traders were being killed one caravan at a time.