Doesn't civilization just literally mean a system of living together in a city? There doesn't need to be any written record of how they did it does there, just evidence that they did?
Urbanization is one qualifier but not the only one. Plus even today we could have such chaos in a town where laws are absent and justice is that dispensed by the strongman/woman warlord and that would hardly be considered civilization.
Uncivilized does not mean stupid or brutes.
What counts as a city? Anyway, we're talking about a concept involving family resemblances rather than an airtight set of sufficient-and-necessary conditions.