The Eighteen Prefectures were definitely the overlords of Dark Thunder Territory. They were deeply rooted in the territory, very powerful, and way above any of the other criminal enterprises.
The Celestial Beast Alliance for example were definitely not weak in terms of their strength with four Ultimate God experts. However, they had never dreamed of comparing themselves with the Eighteen Prefectures.
The reason did not purely lie in strength as it also had to do with the methods they had taken and the nature of their businesses.
However strong the Celestial Beast Alliance was, they were just thieves after all.
Although the Eighteen Prefectures were also thieves, they could be equated to 18 powerful regional political powers to the others.
Anyone of the Eighteen Prefectures was equipped with the means to control a region.
Each of the Eighteen Prefectures had its own very well-organized intelligence department.