George Lucas revealed in a 2002 interview with Time that he was looking for something more than just fashion. He looked back to the women of the Mexican revolution and drew inspiration from their hairstyles.
"In the 1977 film, I was working very hard to create something different that wasn't fashion," he said. "I went with a kind of Southwestern Pancho Villa woman revolutionary look, which is what that is. The buns are basically from turn-of-the-century Mexico."
A Star Wars fan recently took to Facebook to remind people of the revelation after seeing an exhibit about the characters.
"Was at the Star Wars exhibit at the Denver Museum of Art recently and learned that her iconic hairdo was lovingly hijacked from women of the Mexican revolution. This is how you defeat the empire." he wrote.
It's encouraging to see these strong female characters with strong origins (down to their hairstyles!) in film, and Princess Leia certainly was a trailblazer.