The transition from Sui to Tang started roughly around 613 when Emperor Yang of Sui launched his first of three failed campaigns against Goguryeo, and ended in 628, when Emperor Gaozu's son Li Shimin annexed the agrarian rebel ruler Liang Shidu's state of Liang.
We must make sure both the emperor and his officials behave with caution until the end. This way the country shall have long lasting peace, better than the old times
When a government is corrupt and its ruler is failing its people, the people would be pleased to see its collapse. Then the whole country would welcome a new leader.