Amazon's The Lord of the Rings TV show that is being developed by the streamer will need to follow guidelines laid down by the Tolkien estate, as there are rules regarding what parts of the established lore from the books can be changed.
A TV show based on the works of J.R.R. Tolkien is currently being developed by Amazon and details about the production have slowly been revealed over the past few months. The Lord of the Rings TV show will take place during the Second Age, which ended when Isildur cut the One Ring from Sauron's finger. The show has an incredible line-up of creative staff, including people who worked on shows like Breaking Bad, Game of Thrones, and Stranger Things. Markella Kavenagh has been cast as a character named Tyra, though that name might be a decoy in order to avoid spoilers. It was also recently revealed that the first season will consist of around 20 episodes, which is a lot for a brand new show, even one that is based on a famous license.
One of the people hired to work on The Lord of the Rings TV show is Tom Shippey, who is a world-renowned Tolkien scholar and was hired to work on the original The Lord of the Rings film trilogy. Shippey recently spoke to the German Tolkien fan site called Deutsche Tolkien Gesellschaft about the show and was asked about what content the creators were allowed to use.
Amazon has a relatively free hand when it comes to adding something, since, as I said, very few details are known about this time span. The Tolkien Estate will insist that the main shape of the Second Age is not altered. Sauron invades Eriador, is forced back by a Númenorean expedition, returns to Númenor. There he corrupts the Númenoreans and seduces them to break the ban of the Valar. All this, the course of history, must remain the same. But you can add new characters and ask a lot of questions, like: What has Sauron done in the meantime? Where was he after Morgoth was defeated? Theoretically, Amazon can answer these questions by inventing the answers, since Tolkien did not describe it. But it must not contradict anything that Tolkien did say. That’s what Amazon has to watch out for. It must be canonical, it is impossible to change the boundaries which Tolkien has created, it is necessary to remain “tolkienian."
The restrictions on adaptations of Tolkien's work are nothing new and the Peter Jackson movies faced similar restrictions. Gandalf mentions in The Hobbit movies that five wizards came to Middle-earth, but he cannot remember the name of two of them. These wizards are called Alatar and Pallando, but content relating to them appeared in Unfinished Tales and was outside of the boundaries of The Hobbit & The Lord of the Rings, so they had to go unnamed in the films.
The Second Age of Middle-earth encompasses a long stretch of time and there were lots of interesting events that occurred during this period, such as the forging of the One Ring, the birth of the Ringwraiths, numerous wars among the dwarves, elves, and men of the realm, and the Last Alliance against Sauron. The creators of The Lord of the Rings TV show have a wealth of content to draw upon in the Second Age and there is also a lot of room open to tell new stories. The restrictions laid down by the Tolkien estate will ensure that the creators cannot change the history as-written, to prevent them from telling their own version of Tolkien's story.
Source: Deutsche Tolkien Gesellschaft