司马越
Sima Yi was born in 342, to Emperor Cheng and his concubine Consort Zhou, who was also the mother of his only brother, Sima Pi, who was one year older than he was. Later in 342, Emperor Cheng grew gravely ill. Typically, the throne would be passed down to a son, but Emperor Cheng's uncle Yu Bing (), who wanted to control the government a little longer, suggested that, because Jin was then facing the threat of Later Zhao, that an older emperor was needed, and so persuaded Emperor Cheng to pass the throne to his younger brother Sima Yue the Prince of Langya, who was Yu Bing's nephew as well. Emperor Cheng agreed, and after his death, Sima Yue took the throne as Emperor Kang. Emperor Kang created Sima Yi the Prince of Donghai.