Star Trek: 10 Things You Need To Know About The Lost Era

10. … And The Rest Isn't History

The moments after the Dom Perignon hit the Enterprise-B would be the last we would properly spend in what was then a very long gap in Star Trek history: 2293 to 2364. 

Finding and putting dates to Star Trek's future timeline has been complicated! The Original Series maintained ambiguity over the period in which it was set. In his original 1964 Star Trek is… pitch, Gene Roddenberry simply stated that, "The time is 'Somewhere in the future'. It could be 1995 or maybe even 2995." Later, in the book The Making of Star Trek, Roddenberry added,

In the beginning, I invented the term 'Star Date' simply to keep from typing ourselves down to 2265 A.D., or should it be 2312 A.D.? I wanted us well in the future but without arguing approximately which century this or that would have been invented or superseded.

In The Making of Star Trek, it is assumed that The Original Series took place "in the 23rd century." Early reference works, such as Star Trek Space Flight Chronology (1980) and Mr. Scott's Guide to the Enterprise (1987), then tended to place Kirk's five-year mission at the start of the 2200s. 

Then, the Star Trek: The Next Generation Writer/Director's Guide indicated that,

STAR TREK: THE NEXT GENERATION is dated near the beginning of the 24th century. 78 years have passed since the time of Kirk and Spock.

Things were still a bit confusing at the beginning of TNG's first season. In Encounter At Farpoint, Data says that he graduated "Starfleet class of '78." In The Neutral Zone, Data gives us the first ever specific date in the timeline of Star Trek's future history:

Ralph Offenhouse: "What year is this?"

Data: "By your calendar, two thousand three hundred sixty-four."

It was this and a few other "basic assumptions" that allowed the (retro-)dating of Star Trek as we know it today, most notably by Denise Okuda and Michael Okuda in their 1993 work Star Trek Chronology: The History of the Future.