Earlier this year, a student asked me how I thought historians would characterize the period of world history he believed had just begun with Russia’s invasion of Ukraine. I couldn’t resist replying: “I have no idea. I just hope they won’t be calling it the ‘prewar period.’”

But are we, in fact, at the beginning of a new period in history? Many have been quick to affirm the idea. Even before the invasion began, the Wall Street Journal columnist Gerard Baker was opining that “the crisis over Ukraine … marks the definitive end of the post-Cold War era.” And no sooner had Russian forces crossed the Ukrainian border than the Brookings Institution’s Daniel S. Hamilton agreed: “The post-Cold War period has ended. A more fluid and disruptive era has begun.” A few days later, the political scientist Sean Illing called the invasion a “world-historical event,” adding that “the effects of it will likely ripple out for years to come.” All three were confident that one day, historians would begin new chapters in their textbooks with the year 2022.

Historians themselves, though, have never had a single, obvious, agreed-on way of slicing up history into distinct segments, and they quarrel endlessly about how to do so. Some speak of a “long 18th century” that stretches from 1688 to 1815 and others of a “short 18th century” that runs only from 1715 to 1789. Did the Middle Ages end with the Italian Renaissance in the 14th century or with European voyages of exploration in the 15th? Or perhaps the Reformation in the 16th century? Was there such a thing as a “Global Middle Ages,” or does that term impose a European concept on areas of the world unsuited for it? As long as historians disagree about the relative importance of different factors of historical change—i.e., forever—they will disagree about periodization. 

“The pandemic,” Foreign Policy itself proclaimed in March 2020, “will change the world forever.” The actual predictions it elicited on this occasion have, for the most part, stood up quite well. But did 2020 really mark the start of a new era? Today, with the initial shock having receded and with COVID-19 possibly (hopefully) descending to the level of an endemic but manageable disease, its world-changing character seems at least somewhat less apparent.