I got to thinking some more recently about the interrelation of societal advancement and information availability. That got me wondering about the limits.
In short, what is the most advanced society that has been shown to exist with no writing?
Yes, I know "advanced" is way too subjective. So for the purposes of this question, let's replace that with largest in terms of human members of the society. So what was the largest known population of an nonliterate political unit in history?
I'm not interested in parasitic societies like the medieval Mongols, who get what they have only by conquering more advanced literate states (also, the Mongols technically weren't nonliterate after 1204, but hopefully you get the idea).
Also, I'm not concerned here about cause and effect. Perhaps large organized societies naturally create writing when they need it, or perhaps they just can't get past a certain size without it. Either way, I want to know what the biggest was.
At first I thought the Aztecs might qualify, but no they had codexes. The Inca had Quipu. The pre-contact Tongans might be a candidate at around 20k(?), as might Cahokia if they indeed had no writing. Some of the New Guineans might be in the running too, but I don't know how large any of their pre-contact political units ever got.