Zhengyang Pavilion was not a loft rented by an external sect in the Fifth District, but was set up by a certain First Grade Immortal Envoy from an Immortal Mansion.
Although that Immortal Envoy was only a half-immortal, he was an Immortal Rank Alchemist who could refine Immortal Pills. His name was Yan Zhengyang, hence the name of the pavilion, Zhengyang Pavilion.
According to Cang Shaoyuan, every ten years, all Fifth-order Alchemists have a major exchange event. At that time, quite a few First Grade Immortal Envoys will appear. And within ten years between two major exchange events, there is a small exchange event like this one every year, which generally only involves Spirit Transformation cultivators, without First Grade Immortal Envoys of Half Immortal Level.