The Rings of Power draws largely upon tales from The Silmarillion, which many have long considered impossible to adapt in live-action. The book's major events take place across millennia, with the Second Age alone suring 3000 years. As showrunners JD Payne and Patrick McKay have since explained, The Rings of Power condenses Tolkien's Second Age into a single period of time. This is why Isildur is already alive before Sauron's return to Middle-earth, even though the Númenórean hero should be born over 1500 years after the Dark Lord's comeback.
The Rings of Power isn't the first live-action compression of J.R.R. Tolkien's timeline. In Peter Jackson's Frodo receives the Ring on Bilbo's birthday, but keeps it safe in the Shire for another 17 years before Gandalf finally realizes it's probably best the hobbit starts running away. Jackson squeezes those years Frodo spent hiding the Ring into an almost negligible amount of time.
This is an example of a Lord of the Rings movie change that succeeds. Every significant event from those 17 years (Gollum's capture, Gandalf's realization, etc.) can feasibly happen much faster, so Jackson's The Fellowship of the Ring isn't losing material by shortening the timeline. Whether Frodo leaves the Shire after 17 days or 17 years doesn't meaningfully impact Tolkien's narrative or characters, and the faster pacing works better on the big screen. Inevitably, truncating half of the Second Age isn't as problem-free. The Rings of Power appears to be fitting everything from Sauron's return to the Last Alliance of Elves & Men inside Isildur's adulthood, which amounts to a maximum of 200 years. Unlike Frodo's relatively uneventful 17-year calm before the storm in Bag End, many great deeds happen during this period - the creation of the Rings, war against Sauron, the founding of numerous major locations, the rise of fall of Númenór. Even if The Rings of Power somehow can narrow down such a vast history into a single point, doing so would make Tolkien's mythology feel considerably smaller in scale.
How The Rings Of Power Could Adapt Tolkien's Second Age
Was a shorter timeline really the only way Lord of the Rings: The Rings of Power could adapt J.R.R. Tolkien's "unfilmable" The Silmarillion, or could Second Age history have been presented more authentically while still conforming to a TV format?
One possible solution might've been condensing individual sections of Tolkien's Second Age, rather than the whole thing, using lengthy time jumps to spring from one major event to the next. ittedly, it's unrealistic to honor Tolkien's timeline by having Annatar's manipulation of the elves last 100 in-universe years, or for another century to between Sauron forging the One Ring and the outbreak of war. That wouldn't work at all. But if The Rings of Power season 3 ends with Sauron losing the War Between Sauron & The Elves, for example, season 4 could begin 1500 years later with Sauron resurfacing and getting captured by the Númenóreans, as per The Silmarillion. With these multi-century jumps sprinkled through the series at strategic points, The Rings of Power would feel truer to the source material and the timeline suitably Tolkien-esque in length, but the brisk TV narrative keeps moving along steadily.
Because Isildur and Elendil are present from The Rings of Power season 1, this can't happen. Thousand-year time jumps are not conducive to the health of human characters. According to Payne and McKay (via Vanity Fair), this decision was taken to avoid waiting until season 4 to introduce The Rings of Power's major Númenóreans, but whether their early entrance was worth sacrificing the timeline's integrity remains to be seen. One thing's for sure - the stakes are higher than when Peter Jackson decided to kick Frodo out of the Shire early.