Anarchy is a system of law in which those who apply the law don’t have any specially privileged status to do things that would be crimes if other people did them.
For example, taxation is theft. War, as conventionally understood, is mass murder. Arrest for a “crime” with no actual victim is kidnapping.In hunter-gatherer systems, there frequently was no legal prerogative. Roughly, we anarchist-types are simply suggesting that states act like criminals...but because they convince other people to call them "states", they are treated differently. Or maybe it's because they have superior firepower, and people are finitely interested in calling powerful bullies powerful bullies.