The siege on Yang Country was the result of Zhongxuan Chuliang and Zhongxuan Sheng exhausting their political resources to make it happen.
Although it catered to Emperor Qi's desires, it was still made possible by Zhongxuan Sheng's reckless efforts.
Prior to this, after his travels in the Heavenly Abode Secret Land, he widely cultivated his influence in Linzi. Under the guise of competing with Zhongxuan Zun for the position of the Family Head of the Zhong Xuan Family, he made connections with many of Zhongxuan Zun's rivals.
He then staked all these accumulations on the gambling table once again.
He relied on his understanding of Emperor Qi's ambition to rule the Eastern Region, and the opportunity arose with this epidemic in Yang Country!
Jiang Wang didn't ask Zhongxuan Sheng when he had started harboring such great ambitions toward Yang Country.