From Against the Grain by James C. Scott, page 213:
Episodes of collapse are frequently succeeded by what comes to be known as a "dark age." Just as the meaning of collapse merits close and critical inspection, so the term "dark age" needs to be queried: "dark" for whom and in what respects? Dark ages are just as ubiquitous as storied dynastic highpoints of consolidation. The term is often a form of propaganda by which a centralizing dynasty contrasts its achievement with what it casts as the disunity and decentralization that preceded it.
There's a saying that those who do not learn history are doomed to repeat it (actually the original quote is probably "Those who cannot remember the past are condemned to repeat it" - and yes I find it very funny that this quote is not properly remembered).
The problem with learning from history is that the very notion of "history" is a bait and switch. We use it to mean two things:
- Stuff that happened in the past.
- The study of said stuff.
But the study of the past heavily over-represents the sort of thing that leaves stable records. We have access to the physical libraries of the past (except the bits that got burned) but not to the ghost library.
Actual historians do, by and large, understand this of course, but to some extent there's only so much you can do: There's just vastly more information to study that represents what people with power wrote down. The best we can do with the rest is to read between the lines of that and infer what we can from archaeological remnants.
If you're not a historian, you may never really have learned how to engage properly with history (I certainly didn't), and so may have bought into a lot of historical propaganda.
People are, I think, aware of the problem of modern propaganda - we know journalists are mostly somewhere between highly selective and outright lying to us - but we tend to forget that historical records are mostly written by people who were doing the same at the time.
This is before you even get into the problem of modern propaganda efforts which are actively selecting from history to paint a particular narrative - a lot of the people telling us about the glories of the British Empire, for example, know full well how bad it was, they just don't want us to know that.