How many years does the Three-Body Problem story span?
The main storyline runs from 1967 to the year AD 18,906,416 — nearly nineteen million years. Most readers assume the trilogy covers a few decades, from the Cultural Revolution to the moment the sophons lock down Earth's science. That is only the first forty years. From there the clock starts jumping by entire eras, and by the final pages the calendar outside Cheng Xin's window reads almost nineteen million AD. The honest answer is not a number of decades — it is a number that spans most of a species' lifetime, set against the lifespan of the universe itself.
When does the timeline actually begin?
It begins in 1967. That is the year Ye Wenjie watches her father beaten to death during the Cultural Revolution, the trauma that later pushes her to answer an alien signal from the Red Coast base. The famous "do not answer" warning and her decision to reply anyway are the causal origin of everything that follows. The stretch from 1967 to roughly 2007 — when the sophons freeze human physics — is the only part of the trilogy that moves at a normal, generational pace. After that, time accelerates.
How much time passes during the Crisis and Deterrence Eras?
About three centuries. When the Crisis Era begins, humanity learns a Trisolaran fleet is crossing four light years at one percent of lightspeed — a journey of more than four hundred years. That single fact forces the story into a multi-century scale, complete with the Wallfacer Project and hibernation technology that lets characters skip forward in time.
The pivot comes in 2208, when the droplet destroys the human fleet and Luo Ji establishes dark forest deterrence. The 62-year Deterrence Era that follows ends in 2270, when deterrence collapses under Cheng Xin's watch. By then three hundred years have passed, glimpsed through the eyes of hibernators who wake into a different century each time.
What is the 18-million-year jump at the end?
It is the result of relativistic time dilation stacked on top of a mini-universe time gap. After the Solar System is folded into two dimensions, Cheng Xin and Guan Yifan shelter inside a mini-universe only a few kilometers across. A handful of subjective years pass for them. When they choose to return their universe's mass and step back through the door, the clock outside reads AD 18,906,416. It is Liu Cixin pushing relativistic time effects to their absolute literary extreme: a few years for the travelers, nearly nineteen million for everyone else.
Does the timeline go beyond AD 18,906,416?
Yes — by orders of magnitude. The final choice Cheng Xin faces is whether to return mass to the great universe so it can collapse and reset toward its ten-dimensional beginning. That background runs to the universe's full multi-billion-year lifespan and the entire history of the dark forest war that flattened space from ten dimensions to two. So the true span of the Three-Body Problem is not measured in years at all — the human storyline reaches nineteen million AD, but the canvas behind it is the life and death of the cosmos.