The '60s did not really get going in 1960, nor end in 1969. As we know it culturally, the decade began with the JFK assassination in 1963 and ended only with Nixon's resignation 11 years later. Neither, many historians say, did the 19th century finish in 1899. Instead, it continued until WWI — and even as long as the 1930s.

The big picture: Historians call these "long decades" and "long centuries" — super useful constructs for grasping big, prolonged events outside of mere time, and seeing them as eras, zeitgeists and social phenomena.

• So it is with the 20th century, which as an era appears to have pushed straight through to 2016, when it came to a visible close with the financial crisis, Brexit and the election of Trump, experts tell Axios.
• Now we are experiencing the foggy, dust-filled interregnum before a still-undefined 21st century, in which all that seems certain is that powerful forces are deliberately working to pull apart what was built.
• "Trump is the beginning of a new paradigm," says Charles Kupchan, a professor at Georgetown University.

The backdrop: The 20th century's defining moment was WWII and its aftermath, producing the long, great power peace, broad prosperity, a decline of poverty and greater health, not to mention the transistor and space travel.

Ian Bremmer, president of the Eurasia Group, tells Axios that this epochal break actually precedes Trump, whom he calls a function of the age rather than its impetus.

• The new age "was coming no matter who the Americans elected," Bremmer says. "It's more about the rise of China, the divisions in the trans-Atlantic relationship and within liberal democracies themselves, [and] the willingness of the Russians to try to exacerbate those divisions."
• Bremmer thinks the new order won't begin to be decipherable for another decade.
• That is "in part because these U.S. and European issues need to play out. And perhaps in larger part because, [Chinese President] Xi Jinping notwithstanding, China isn't really ready yet for the global stage."