I believe the answer is: <span>antisocial personality disorder
People with </span>antisocial personality disorder is characterized by the lack of empathy that caused them to constantly violate/damaged the rights and well being of other people. A<span>ntisocial personality disorder could be caused by both genetics and psychological trauma about human relationship in the past</span><span />
1. The rulers who came to power after Charlemagne failed to defend the empire.
2. Europe was threatened by Muslims, Magyars, and Vikings in the 9th and 10th centuries.