Darkness is the norm, Jim points out:
Copper production shows three peaks: The Roman Empire in the west, the Song Dynasty, and modernity.
The Roman Empire in the west and the Song Dynasty had about seven times the preceding and following level of copper production, thus while those civilizations were going concerns, they had far more production and wealth than the rest of the world put together.
When the Roman Empire in the West fell, its GDP dropped about a hundred fold.
So, looking at the past few thousand years, the norm has been relatively brief periods of civilization in relatively small parts of the world.
I would guess the problem is that the state lacks the cohesion and self discipline necessary to refrain from devouring civil society, and anarchy lacks the cohesion necessary to keep the roads safe and property rights secure. Technology can advance during anarchic periods, often quite rapidly, but the amount of wealth, as indicated by copper production, shipwrecks, and such, tends to be very low indeed during such periods. Despotic states, on the other hand, have higher wealth, probably because they can make the roads safe over a large area, but are apt to end technological progress, and often reverse it.