Most assertions about the nature of those societies are based on ignorance. Most relevant to your comment, they tend(ed) to maintain rules, conventions, personal property, arbitrate disputes, take care of the weak, and do any number of other things considered impossible without government. Various types of egalitarian social order have existed, it isn't one monolithic concept, and it certainly doesn't necessarily result in chaos or might-makes-right.
If you want specific examples and actual information, take the time to read the pdf. It is written by an anthropologist, so it is his gig to footnote all this stuff.
But to do the other things discussed, other than organized warfare, they seem to work just as well as anything else.
I think this point is important when evaluating the need for government in a variety of other contexts, other than war.
