What is the purpose of Emperor Wu of Song's extermination of Sima Yi's descendants?

During the Eastern Jin Dynasty, the system of gate valve was strict, and Emperor Wu was born in humble background. Even though he was in power, the nobles still despised him and didn't really support him. Although Emperor Wu of Song greatly weakened Sima's power before the Jin Dynasty, Sima was still a force to be reckoned with. After Emperor Wu of Song proclaimed himself emperor, a large number of Sima families fled to North Korea, which combined with the influence of North Korea and posed a great threat to Emperor Wu of Song. What's more, Cui Hao, the minister of the Northern Wei Dynasty, wrote to Mao that "Sima's family should be preserved and Liu's family should be destroyed", so once the Northern Dynasty attacked, these people would definitely support the former emperor or Sima's family. Sima Chu is not the son of Sima Yao, nor after Sima Yi, but after Sima Yi. Because Sima Yi lost his heir, Sima Jia later adopted Sima Chu as the son of Sima Yao in order to continue the incense, but in fact Sima Chu's father was called Sima Rong. Sima Fu (such as Sima Guang) and Sima Xiangru are the only surviving descendants of Sima Ba in Sui and Tang Dynasties.

The return of China's ancient books was mostly written by scholars in Wei and Jin Dynasties, and its achievements were far superior to those of any emperor. All this is the result of the ideological guidance of Sima family, which influenced Sui, Tang and Song Dynasties. After Emperor Wu of Song ascended the throne, he also ordered the slaughter of the Eastern Jin royal family during the Liu and Song Dynasties. The reason is that the political pattern of the Eastern Jin Dynasty was that the royal family and the gentry ruled the world, which led to the lack of imperial power and the constant domestic political struggle. In order to stabilize the country, Liu and Song dynasties appointed children from poor families to take charge of state affairs, so as to eliminate the influence of aristocratic families on imperial power.

In the era of Emperor Wu of Song, political affairs were greatly influenced by aristocratic families, and the support of big families could even affect the rise and fall of national politics and national strength. So although Emperor Wu of Song became emperor without any support, he still had to rely on guns to maintain his rule. On the way to regime change, Emperor Wu of Song relied on the name of the emperor to promote the political status of the children of the poor. However, when Emperor Wu of Song usurped the throne and became king, the biggest aristocratic gate in front of him became the imperial Sima family, so the Sima family became the most unstable factor in the Liu and Song Dynasties. Besides, when Emperor Wu of Song usurped the throne, he was old and Liu Yuxin Yifu was young, so what Emperor Wu of Song needed most was to eliminate Sima Shi.