not only was it long period but the Middle Ages are only ever brought up by people educated by a Western/ized idea of history.
My point stands because we would never hear of systems that "worked" in a decentralized way because required power structures would have never been in place for them to leave any impact that people will feel should be noted in the history books. James C Scott[1] does a great job tracing decentralized societies fleeing the Chinese empire over a period of several hundred years and settling in the hard to access hills of South East Asia.
A successful decentralized society wouldn't be in our history book because the measure of success is different in these systems. In fact things that are a failure in one system are a success in the other.
In the same way today, groups like the Jawara/Andaman or similar tribes will always remain a footnote in our books, at least until their successful assimilated into our own "superior" culture, and then we give them an honorary mention (= by then their way of living is destroyed ofc).
Another way to read this (and the way I personally do) is that a successful decentralized alternative is often the by-product of (an over-reaching) centralized system. Take a look for what the state labels as crooks, outlaws, degenerates, pirates, insurgents, terrorists, or anyone they are struggling to tax and prosecute, ... in modern times Roma/gypsies are the only ones left who come to mind. Everyone else we eradicate!
[1] https://en.wikipedia.org/wiki/James_C._Scott#The_Art_of_Not_...
So we can have more devolvement, an endless argument here in the UK, but centralised money structures, standards bodies, transport networks, etc are required for this to be feasible. Already we complain that the more niche ideas can be more successful in the US because there's a larger home market.
To paraphrase Zizek's quote on the end of capitalism: We are so far down that road, that it's easier to imagine the end of the humanity than it is to imagine humanity living in a decentralized society.
some of the people (other than Scott) who influenced my thinking on this would be:
Berger: https://en.wikipedia.org/wiki/Peter_L._Berger (especially http://perflensburg.se/Berger%20social-construction-of-reali...)
Jacques Ellul https://archive.org/details/JacquesEllulTheTechnologicalSoci... (also Propaganda)
and Nassim Taleb (e.g. his view on Switzerland) ...
also I'm admittedly thin on anthropological reading (still have Agner Fog's book on my list since ages: https://www.agner.org/cultsel/warlike_peaceful.pdf)
Caroline Humphrey also gave a talk [1] that I've wanted to cite, but haven't found an excuse for. She's not against the idea, but she brings up a lot of issues with applying it to areas like like Tyva/Khövsgöl, as these were clearly state-spaces despite fitting all the other characteristics. She runs into basically the same criticism as Tenzin in that zomia doesn't encapsulate precisely what we intuitively understand as people about these marginal border spaces.
[1] https://www.researchgate.net/publication/297392497_IS_ZOMIA_...