In the late Three Kingdoms, Sima Yi's grandson seized the throne, which dynasty was established?

Sima Yan, the grandson of Sima Yi, seized the throne and established the Jin Dynasty. In the second year of Emperor Xianxi (265), Sima Yan attacked his father. A few months later, Cao Huan, the Emperor of Wei Yuan, was forced to abdicate, with the title of Jin, its capital being Luoyang and Taiyuan. In the fifth year of Xianning (279), Du Yu and others were ordered to divide their forces to attack the State of Wu, destroy it the following year and unify the whole country.

Sima Yan (16,236-May 290), namely Emperor Wu of Jin Dynasty (reigned from 265 to 290). An Shi, born in Wenxian County, Hanoi (now Wenxian County, Henan Province), was the founding emperor of the Jin Dynasty. The grandson of Sima Yi, the emperor of Jin Dynasty, the nephew of Sima Shi, the eldest son of Emperor Wen of Jin Dynasty, and the stepfather of Emperor Wen of Jin Dynasty.

Extended data history evaluation:

Sima Yan reigned for more than 20 years. He has made outstanding contributions to the development of economy and culture. However, influenced by the times, the political system basically followed the enfeoffment system since the Han Dynasty, which seriously weakened the consolidation of centralization. In addition, in his later years, he lived in luxury and corruption, publicly sold officials, and had nearly 10,000 concubines in the palace. Officials at all levels ignored political affairs, and extravagance prevailed, which accelerated the demise of the Western Jin Dynasty.

Shortly after the death of Emperor Wu of Jin Dynasty, the "Eight Kings Rebellion" occurred in the Western Jin Dynasty, which lasted 16 years. Coupled with constant natural disasters and epidemics, working people began to die or be displaced in large numbers, and Taikang's prosperity soon lost its former glory.

References:

Baidu Encyclopedia-Sima Yan