Palpatine: Did you ever hear the Tragedy of the Star Wars Expanded Universe?

Anakin: No.

Palpatine: I thought not. It's not a story Disney would tell you. It's a Space Opera legend. The Star Wars Expanded Universe was a shared universe of space opera literature so huge and so old, its writers could use their skill to influence George Lucas to create... new stories. Its greatest writers had such knowledge of the mechanics and history of the shared universe, that they could even retcon the characters they cared about... from death.

Anakin: They could actually... save fan-favorite characters from death?

Palpatine: The Expanded Universe is a pathway to many stories some consider to be Legends.

Anakin: What happened to it?

Palpatine: It became so big... the only thing it was afraid of was losing its status, which eventually, of course, it did. Unfortunately, it showed its successor everything it created, and then one night, Disney killed it in its sleep. Ironic. It could retcon others back from death, but not itself.

Anakin Skywalker: Is it possible to learn these stories?

Palpatine: Not from a Mouse.