	One additional trend that started with Emperor He was the lack of imperial heirs - most of Emperor He's sons predeceased him, and at his death he had only two live male children, neither of whom survived him long. Whereas many dynasties had succession crises triggered by an emperor's many sons vying to succeed him, in the case of the Eastern Han crises were triggered by the lack of direct male line heirs, further adding to dynastic instability.