[RoosterRedux]

Fighting, competition, ambition, defense of one's own family/estate, argument, misunderstanding, physicality, testosterone/manliness, love (two or more men loving the same woman), jealousy.

Those are just a few of the things I toss out there to suggest that the absence of war (large or small) is impossible over a protracted period of time.

Like it or not, fighting is just human nature.

In fact, it is the threat of violence that helps maintain the peace.

[Cronos]

Fighting for what you state seems to have happened -- if you read the article archaeology has found cases of violent deaths

But no wars between cities or organized warfare at all.