One could describe Ouyang Shuo's strategy toward the territories at his border as cultivating poison.
Ouyang Shuo had always viewed Lianzhou Basin as something he owned. He wouldn't allow any others to corrupt it. The other territories in Lianzhou Basin weren't even on the same level as the Shanhai County.
After all, destroying their territories would mean losing that important growth stat. Hence, Ouyang Shuo naturally wouldn't be too rash. Instead, he just watched closely as these territories developed. They were similar to a blood-making machine which provided the Lianzhou Basin with refugees.
He had to wait for the basins to start and connect with Shanhai City. Only then could he possibly spy on and see some of the secrets of his territory. After that, Ouyang Shuo would make a move and remove them from Lianzhou Basin.