How did the northern migration and suppression of the noble clans of the Sui Dynasty hit the separatist forces in the south of the Yangtze River?

After the death of Chen, although most of the noble families in the south of the Yangtze River moved north, the local tycoons and the so-called "Xidong marshals" who were expanding their power during the Liang and Chen dynasties still retained their strength. The officials sent to the south of the Yangtze River during the Sui Dynasty were all northerners and did not respect the privileges of the local powerful. The powerful felt that unification harmed their interests. In the winter of the 10th year of Emperor Kaihuang's reign, anti-Sui riots broke out throughout the old territories of the Chen Dynasty. At that time, there were rumors that the Sui Dynasty wanted to move all the people from Jiangnan to Guanzhong, so the powerful people were able to gather people, tens of thousands in large groups and thousands in small groups. The Sui Dynasty sent Yang Su as the general manager of the march to lead the troops to suppress it. Unification is the general trend, and separatism and separatism cannot truly gain the support of the people of Jiangnan. The powerful powers are on one side and their strength is scattered. The Sui army defeated them one by one, and they were pacified about the next year. The northward migration of the noble clans and this suppression dealt a heavy blow to the separatist forces in the south of the Yangtze River.