At the start of March 2019, Amazon revealed that the series would be set in the Second Age of Middle-earth, thousands of years before the story of The Lord of the Rings. Shippey explained that the series was not allowed to contradict anything that Tolkien had written about the Second Age and would have to follow the broad strokes of his narrative, with the Tolkien Estate prepared to veto any such changes, but Amazon was free to add characters or details to fill in the gaps between Tolkien's works. The series is also only allowed to adapt and reference content from the Lord of the Rings books and their extensive appendices rather than any of Tolkien's other books that explore the Second Age such as The Silmarillion. The Tolkien Estate retained the rights to the events of the First Age while Middle-earth Enterprises held the rights to the events of the Third Age (as seen in The Hobbit and The Lord of the Rings films), so the series was also not allowed to explore those. Shippey felt this left the series with a lot of scope for interpretation and free invention.