Complex sentence: During his reign, regents and warlords dominated the Jin regime, and at one point, in 403, the Jin regime was usurped by the warlord Huan Xuan, and while Emperor An was restored in 404, the Jin Dynasty was nearing its end.
Split into simpler sentences: During his reign, regents and warlords dominated the Jin regime. In 403, the Jin regime was usurped by the warlord Huan Xuan, and while Emperor An was restored in 404, the Jin Dynasty was nearing its end.