This is when The Empire, or some other organization, is somehow estimated to last a certain amount of time. 1,000 years is common, but there are likely other time frames. The important thing is that this is about assuming the length beforehand, not how long it actually lasts.
Sometimes this assumption can be based on a prophecy that states the length of time. Of course, even if the prophecy is correct, that doesn't preclude the many ways there can be a Prophecy Twist. Perhaps the organization will last that long, but not in the way its creators intended. Say if the Evil Overlord founds it, but The Hero slays him, and rules instead. Or, at the end of the stated time, the downfall of the organization may be so catastrophic that it undoes any impact the organization would have left.
- In Gladiator, that is how long Commodus wants his incestuous line to last, when he thinks he's won completely.
- Referenced several times in the World War II drama Conspiracy, which takes place at a time when the Nazis were absolutely convinced that they were moments away from victory.
Neumann: Neumann, director of the Four-Year-Plan. Whom may I be speaking to?Klopfer: I speak for Martin Bormann, of the Thousand-Year-Plan.
- In Star Wars Attack of the Clones Palpatine references the thousand years of the Republic. In A New Hope Obi-Wan refers to a thousand generations (aprox. 25,000 years).note
- The City of Ember was designed to last exactly 200 years and no longer. Too bad the note meant to inform the populace of this got lost.
- In the Foundation books, Hari Seldon determines that the fall of the Empire is inevitable, to be followed by 30,000 years of chaos before a new empire arises. He puts into place a plan that would rebuild the empire in only 1,000 years. In a curiously tasteless regional allusion, the German first edition was actually released under a title translating to "The thousand-year plan".
- According to the 19th century pre-millennial interpretation of The Bible, after Armageddon, Jesus will reign over the Earth for this amount of time before dad Jehovah steps in.
- The above interpretation of The Bible takes place in Kingdom Come from the Left Behind series, during which only "glorifieds" and "naturals" who have put their faith in Jesus Christ will be allowed to live to the end of the Millenium, while "naturals" who stay unbelievers by the time they reach 100 years of age will die and go to Hell. The Other Light faction sees God Is Evil because of this and has prepared for this contingency by passing down their teaching to the next generation of its converts so that the generation that gets to confront God and Jesus at the end of the Millennium will be "assured victory" when Satan is released. Unfortunately for them, it didn't turn out as they hoped.
- The trope is mentioned in The Elenium, where a reference is made to a historical figure creating an empire of a thousand years that barely outlived its founder.
- The Lord Ruler from Mistborn called his reign "The Final Empire", because he believed that the empire (and he himself) would last forever.
- The Chung Kuo boast of their reign having lasted three thousand years. However the reader knows that history has been rewritten so that the Chung Kuo are an ancient Chinese empire that conquered Western Europe in the days ancient Rome, whereas it's actually just 200 years old.
- The Lannisters in Game of Thrones have this goal in mind. In Season 1 Lord Tywin discusses the war plans with his son Jaime, explaining that the events of the coming months will either cement a Lannister/Baratheon dynasty on the Iron Throne that could last a thousand years, or they could collapse into nothing like the Targaryens (who made it to 300 years themselves).
- In The Wild Wild West episode "The Night of the Red-Eyed Madmen", General Grimm is A Nazi by Any Other Name who wants to take over the American Southwest and place it under strict military rule. His second-in-command predicts that his reign will last "a thousand years".
- The Book of Revelations says Christ will reign with the Saints for 1,000 years, during which time Satan is bound.
- Millennial Kingdom, as per Shin Megami Tensei
- Irregular Webcomic!: Nazi Science sneers at your pathetic notions of arithmetic!
- The "Woodland Critter Christmas" episode of South Park, where the The Antichrist is supposed to "bring a thousand years of darkness to the forest".
- Spoofed in Xiaolin Showdown. One episode revolves around them locking up their dragon Dojo for the day, because on that particular day he'll turn evil, grow two heads and devour all of the magical Shen Gong Wu items, leading to 1,000 years of darkness. The spoof comes from the quote above.
- In The Legend of Korra, Harmonic Convergence is a supernatural event that occurs once every 10,000 years, in which the spirits of harmony and chaos, Raava and Vaatu, must battle to determine which force will reign until the next Harmonic Convergence.
- My Little Pony: Friendship Is Magic begins with Twilight Sparkle reading an old legend that states that the stars would aid in the escape of the Nightmare Moon on the longest day of the 1000th year of her banishment, when she would bring about nighttime eternal. Princess Celestia reigned as sole sovereign during this entire time.
- Older Than Feudalism: 1,000 years was the prediction for how long The Roman Empire would reign made by Cicero, which is probably the Trope Codifier in the Western Hemisphere. (He wasn't entirely wrong. The Eastern Roman Empire lasted until 1453,note and the Ottoman Emperor claimed the title of "Kaysar-i-Rum" "Caesar of Rome" until 1922.)
- Ancient Chinese emperors tend to be greeted with "萬歲!" ("May you reign for 10,000 years") but most dynasties only last about 400 years or so.
- There is a careful delination with these acclamations, Empresses are acclaimed "A thousand years!" And sometimes, particularly powerful officials would be sarcastically greeted (not out loud, obviously) with "Nine thousand years!"
- Adolf Hitler and Those Wacky Nazis invoked this trope by promising a thousand-year Reich. Berlin would be the new world capital of a greatly expanded "Germania". It lasted merely twelve.
- "Tenno heika banzai" the Japanese battle cry that gives the phrase "banzai charge" means literally "Ten thousand years! [ to the Emperor]" Since the Emperor was understood to have a normal human lifetime, this wasn't meant literally.
- The Holy Roman Empire was, at the time of founding, considered a continuation of The Roman Empire and the fourth and last "world monarchy" predicted by the Book of Daniel (after Babylon, Persia and Macedonia). It was believed that, since Rome was the last worldly empire, it would last literally until Judgement Day. (When it didn't, that's how the Fifth Monarchists became a thing during the English Civil War.)
- In terms of a single Royal Family managing to pull off a Thousand Year Reign, one of the few examples is the Capetian Dynasty. The current, as of 2018, king of Spain is a direct male-line descendant of Hugh Capet, who was himself crowned King of the Franks in 987. For more than a thousand years, they have almost continuously been kings of something, with few interruptions.