After looking up further into it, looks like we were both wrong ?
I was talking about the Crisis of the Third Century, when you can see the debasement of currency getting really bad. The timeline seems to be something like
plague + climate change + weak institutions => civil wars => civil wars + plague + famine + barbarian invasions => almost miraculous stop to the collapse
Alaric and the Huns were a couple of centuries later, though it does seem like Sarmathians played a similar role at that point ? But Roman legions were still far off from recruiting non-citizens at that point, and even when barbarians invaded, they did not stay for long ?
My confusion probably came from that debasement - that was a big drop, but the debasement had started significantly earlier !
So if we look at indicators like denarius silver content, lead pollution, shipwrecks... they all seem to point to the beginning of the decline around 125 AD, so about 125 years before that big penultimate crisis ? I will have to look at what then some other day though...
Depends then on your definition of "collapse." The Roman Empire was in decline for two centuries prior to the sacking of Rome by Alaric. But I wouldn't go so far as to call that systemic collapse. And the point I was making was very specifically about that apocalyptic scenario. User progne claimed that we're in some sort middle ground between cycles of collapse and stability, but I just don't see that being true historically. Business cycles, yes, but systemic collapse? No, collapse is still an exceptional, aperiodic event.
Decline precedes collapse a bit like old age precedes death.
That would be three centuries prior.
The 3rd century crisis, two centuries prior to the (2nd) sack of Rome (1rst one was 8 centuries before that), already looks like a stopped, and partially recovered from, systemic collapse to me.
(Also even collapse isn't instant - Rome got sacked 3 times in a span of 62 years !)
I'm not progne, so I would rather say that the cycles are about growth and decline, with "collapse" being notable because things can decline much faster than they can grow (again, consider gestation - birth - early years vs death, especially accidental death). (And yes, business cycles are also like this, on a shorter timescale.)
As for guessing were WE are at, consider how the combination of growth then of decline also results in a semistable brief peak : we seem to have had it in the 90s. Unless of course you also consider the (ex-)URSS, which had a first collapse at that point, at which point the peak was probably more something between 1945-1970-1991. But then previously we were exclusively talked about the Western Roman Empire, while the Eastern Roman Empire survived for another millennium !! (Including recapturing Rome, which then was sieged/sacked two more times.) I guess you might want to look into that for counter-examples ?
I was talking about the Crisis of the Third Century, when you can see the debasement of currency getting really bad. The timeline seems to be something like
plague + climate change + weak institutions => civil wars => civil wars + plague + famine + barbarian invasions => almost miraculous stop to the collapse
Alaric and the Huns were a couple of centuries later, though it does seem like Sarmathians played a similar role at that point ? But Roman legions were still far off from recruiting non-citizens at that point, and even when barbarians invaded, they did not stay for long ?
My confusion probably came from that debasement - that was a big drop, but the debasement had started significantly earlier !
So if we look at indicators like denarius silver content, lead pollution, shipwrecks... they all seem to point to the beginning of the decline around 125 AD, so about 125 years before that big penultimate crisis ? I will have to look at what then some other day though...