An ambiguous time period is where the series takes place at a certain time in the past or future and in the same universe as ours except for the story elements added by the author but doesn't state anything specific. This is either because the time period is completely unmentioned, mentioned but elements of the story or Word of God state that the fiction uses a different calendar than ours. Sometimes Anachronism Stew will unintentionally (and sometimes intentionally) confuse viewers into wondering when the time period takes place in. This can still happen in works that take place in a completely different universe as ours when there's an overarching timeline but it's very difficult to pinpoint where in that timeline the events currently being described take place in. When the ambiguous time period is obviously not long ago than it's and example of Present Day Past. This trope is the temporal version of Where the Hell Is Springfield?. Contrast Period Piece and Unintentional Period Piece. Anime
- Gundam takes place in the future, but thanks to their excessive use of Alternate Calendar (several, in fact) how far in the future is impossible to pinpoint.
- The first Dragon Age comic mini-series is notoriously hard to fit into the series' overarching timeline.
- The Lion King gives no indication of what time the story takes place. Which is part of why it is so appealing. It could be happening in 1607 or 100 years in the future.
- Dodgeball: A True Underdog Story: Word of God has it that the movie was supposed to take place in the early 1990s, but the case of Anachronism Stew including Peter renting Mona Lisa Smile on DVD, as well as digital cable being in existence would suggest otherwise; it pretty much looks as if it could have been set in the present day.
- Most of the time, The New Adventures of Pippi Longstocking seems to be set around the 1940s (when the first books were written). However, the characters are shocked when a local man "invents" a flying machine and Pippi's sailing adventures with her father seem to be out of the 1600s.
- 10,000 BC appears to be set in the prehistoric times, with the main character encountering both a wooly mammoth and a saber tooth tiger. However he ends up somewhere that appears to be ancient Egypt or at least Mesopotamia (an emperor is having a large pyramid built).
- Robert E. Hopward's Conan the Barbarian stories take place sometime between 20,000 B.C. and 9,500 B.C. Or as his short story "The Phoenix on the Sword" puts it, "Between the years when the oceans drank Atlantis and the gleaming cities, and the years of the rise of the Sons of Aryas."
- The Doctor Who episode "The End of the World" where Sol explodes from old age, destroying the Earth in the process, takes place in the year "5.5/Apple/26."
- Several time periods you visit in Final Fantasy XIII-2 are labeled simply "??? AF" in the Historia Crux, meaning these episodes take place After the Fall but how many years after is unclear.
- Nigel from The Lost Crown never does get a straight answer when he asks what year is it in Saxton, a region filled with anachronisms due to its numerous hauntings.
- Live A Live avoids specifying dates at which chapters occur (although the timeframes are much clearer). Logs in Science Fiction chapter even go so far as to hide dates with Xs (although the "copyright" text in Captain Square minigame makes it clear it takes place no earlier than 22nd century).
- Word of God states that the calender saying that the year is 3031 in Ava's Demon is not the BCE/CE calender we're familiar with.
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