Final answer:
In early history, personal revenge was often considered obligatory in many societies, including the Northeast region where vengeance and warfare were closely linked.
Step-by-step explanation:
In early history, personal revenge was often considered obligatory in many societies. This was particularly prevalent in the Northeast region, where warfare and vengeance were closely linked. Groups sought to avenge those killed in wars or skirmishes, resulting in a cycle of war known as the 'Mourning Wars.' Revenge was seen as a means of achieving justice and maintaining cosmic order through ceremonies of warfare, torture, and sacrifice. Examples include the torture and sacrifice of prisoners and the consumption of their flesh to ingest the enemy's strength.