Emperor Mu of Jin

Emperor Mu of Jin (simplified Chinese: 晋穆帝; traditional Chinese: 晉穆帝; pinyin: Jìn Mù Dì; Wade–Giles: Chin Mu-ti; 343 – July 10, 361), personal name Sima Dan (司馬聃), courtesy name Pengzi (彭子), was an emperor of the Eastern Jin Dynasty (265-420). While he "reigned" 17 years, most of the years were as a child, with the actual power in such figures as his mother Empress Chu Suanzi, He Chong (何充), his granduncle Sima Yu the Prince of Kuaiji, Yin Hao, and Huan Wen. It was during his reign that Jin's territory temporarily expanded to its greatest extent since the fall of northern China to Han Zhao, as Huan destroyed Cheng Han and added its territory to Jin's, and Later Zhao's collapse allowed Jin to regain most of the territory south of the Yellow River.

Sima Dan was born in 343, during the reign of his father Emperor Kang, by Empress Chu Suanzi, Emperor Kang's wife. He was his father's only son. When he was only one year old in 344, Emperor Kang grew seriously ill. His granduncles from his paternal grandmother's side, the key officials Yu Bing (庾冰) and Yu Yi (庾翼), wanted to support his granduncle, the son of his great-grandfather Emperor Yuan, Sima Yu the Prince of Kuaiji, as the new emperor, but Emperor Kang accepted the advice of another key official, He Chong (何充), and decided to pass the throne to Sima Dan despite his young age. (He Chong had, two years earlier, given identical advice to Emperor Kang's older brother and predecessor Emperor Cheng (i.e., he should pass the throne to a son), advice which was not followed.) He therefore created Sima Dan crown prince. He died less than a month later, and Crown Prince Dan succeeded to the throne as Emperor Mu.

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