There are certain very specific, unsustainable periods of history.
The Golden Age of Piracy lasted from the 1650s to the 1730s, and was really three different waves of piracy that all had their own specific causes and characters. My personal favorite has always been the post-Spanish Succession period, when a bunch of sailors and privateers were left unemployed and turned en masse to piracy since those were the skills they'd picked up during the war. This supply of pirates was obviously non-renewable.
The Wild West lasted between 1865 and 1895, depending on who you ask, not even a full human lifetime. It's a very narrow band of time, and of course it wasn't sustainable, there was only so much land to colonize.
There are lots of these times of change, conquest, colonization, and war, particularly in the last three hundred years. I always think they're interesting, mostly in how quickly the course of history moves on to some other relatively more steady state.
There's a thing that speculative fiction does where it stretches specific periods out to extremes, most notably with Medieval Stasis, but I think it's far funnier when applied to these tiny slices of history that have ballooned in the public consciousness. Either it takes heroic feats of worldbuilding to make it make sense, or everyone is just sort of okay with the idea of a Golden Age of Piracy that's implied to have lasted for a millennia.
