Emperor Zhen has been feeling overwhelmed recently; he has neither the mood nor the energy to focus on Dadui, which doesn't border Dazhen.
Spending a lot of time and energy to weaken the vassals was actually out of necessity.
The territory of Dazhen suitable for survival, or rather, the livable areas, has been continuously compressed over the past two hundred years, while the Sealed Kings occupy the warmest and most fertile land.
The accumulated conflicts have completely erupted under such circumstances, forcing Emperor Zhen to make a firm decision to deal with the Sealed Kings, whose power has become too entrenched to be removed easily.
This is a crisis, but also an opportunity; in the end, Emperor Zhen indeed succeeded.
It was precisely after reducing the vassals that a large amount of land was freed, alleviating most of the internal tensions within Dazhen and strengthening centralization.
