As part of the oral history of “Star Wars: Episode I — The Phantom Menace” published on StarWars.com in 2019, George Lucas talked about basing the plot of his “Star Wars” prequel trilogy on the backstories he had written to establish the world of “Star Wars” prior to the very first film. It’s been widely reported that Lucas came up with a lot of background information while making the original 1977 film that was ultimately cut from the movie, such as a six-paragraph opening crawl that Brian De Palma helped edit down.
According to Lucas, he had to come up with an explanation of what the Jedi were, what the Sith were, and how the Empire came to be. Though the word Sith wasn’t uttered until “The Phantom Menace,” the word was included in a rough draft of the first film written in 1974, which refers to Darth Vader as a “Dark Lord of the Sith.” Likewise, the novelization of the original “Star Wars” retains some of this backstory concerning Palpatine’s rise to “President of the Republic” before declaring himself Emperor.
“I spent a lot of time in developing those elements, and what each planet did, and why they did it the way they did,” Lucas explained. “So I had all this material. A lot of the story elements were givens.” Even the concept of the midi-chlorians and their role in the birth of Anakin Skywalker was reportedly conceived by Lucas as early as 1977, according to the book “The Making of Star Wars.”
As Lucas told it, he had to come up with in-universe explanations for the many, many sci-fi concepts the first “Star Wars” was to introduce, and his scripts for the prequels was mostly his way of filling in the gaps in his backstories.