The proposer of this suggestion is Lady Milra, who is the city lord of Arabey City, the biggest backer and financier behind the Red Crow Mercenary Brigade. Originally, the contract to purge the Rocklands signed by the Royal Family and the Red Crow Mercenary Brigade was facilitated single-handedly by Arabey City.
When they initially pushed the Red Crow Mercenary Brigade to purge the Rocklands, it was not out of sheer self-interest but for the sake of the bigger picture.
At that time, Tivandun had not yet joined the Komeer Kingdom; Arabey City was located at the frontier border. Once the monsters from the Rocklands surged out and breached the border, they would be first to bear the brunt.
However, as the investment continued to increase, and Tivandun submitted, the area between the two cities became fertile ground harboring great benefits for Arabey City, things that could not be overlooked.