The three forces had their own specialties.
First was the imperium led by Li Jialing and Li Linghai.
Although they had suffered heavy casualties in the twenty-year-long counterattack of the imperium, the revolution of the civil war, and the defense of the imperial capital, to the point that they had to be rescued by the federation at the most critical moment, the Imperium of True Human Beings was still the most influential force in the civilization of mankind after all. It was a standard example of 'a lean camel is still bigger than a horse'.
Other than anything else, at the very least, the number of Divinity Transformation Stage Cultivators, especially battle-type Divinity Transformation Stage Cultivators, far exceeded that of the federation and the Sanctuary Alliance.