Seems obvious to me. Lose a war and run away. Their mission: simple survival.
Wars are endemic in more primitive societies. An excellent book on the subject is: War Before Civilization.
another arg is that colonization in the South Pacific accomplished 2 goals:
1. reduce conflict within the settlement.
2. reduce drain on limited resources.
I think Diamond’s “Collapse” mentions something on these lines. Either way, run for your life or voyage out to find new resources. In any event people were travelling more than we have imagined/