This is why I think anarchy is unsustainable.

If everyone is a warlord, the warlords will eventually form a hierarchy, again. There will always be someone who warlords better than someone else. One warlord will be overtaken because he's ill or old, or you're desperate to take his women or other property, or he's away traveling. So, warlords will begin joining forces to protect their property and need some sort of agreement on how to do so, and then you are right back at a state.

Anarchy depends upon all warlords remaining atomized and peaceful, forever.