in 5 ce, wang mang, then already nearly unlimited in power as the imperial regent and fearful that the 13-year-old emperor ping, once grown-up, would retaliate against him for having slaughtered his uncles in 3 ce, murdered emperor ping by poison. because the young emperor had not had any children by his wife empress wang (wang mang's daughter) or any of his concubines, there was no heir. emperor ping's grandfather, emperor yuan, had no surviving male issue—of his three sons, emperor cheng had no issue, and sons of the other two, liu kang, prince of dingtao (劉康) and liu xing, prince of zhongshan (劉興), had succeeded to the imperial throne (as emperor ai and emperor ping, respectively) and died without issue. the descendants of emperor ping's great-grandfather emperor xuan were therefore examined as possible successors.