These people were, in fact, Qi Cultivators from the Soundless Gate Sect.
The one who was addressed as senior brother, was a Sixth Stage 'Tongyou' of Qi Refining.
They had been at war with Beigao Country recently. The morale on the battlefield was far fiercer than within the city, but the country still needed people to stay and guard.
Hence, these Sixth Stagers needed to take turns guarding the city, also as a form of recuperation.
He was one of them, had previously sustained serious injuries from a Dharma Technique of a Beigao's Sect on the battlefield, and had returned to the country to recover.
To recover quickly, naturally, some changes needed to be made. Relying on the old methods of driving mortals to ruin was too slow, not to mention waiting for areas to become haunted by demons or monsters.
Coincidentally, the Wealth and Power Clan had sent people to make contact, hence triggering this confrontation.