Teaching your neighbors how to farm sounds like a good way to prevent invasions to steal your own food. That’s in addition to the trade opportunities and alliances forged by such a practice. I imagine the indians who taught pilgrims how to cultivate corn were of a similar mindset.
Then when your neighbors are nice as prosperous you can go a-viking and take their stuff.
Trade seems to have worked as well -- but better safety arrived with standing armies. A population has to be able to support their own defenders over and above what they need to support themselves.