
Apparently, Star Wars felt that "Before the Battle of Yavin" and "After the Battle of Yavin" were not clear enough.
The new eras are the High Republic, the Fall of the Jedi, the Reign of the Empire, the Age of Rebellion, the New Republic, and the Rise of the First Order.
These eras include all of the Star Wars stories fans are familiar with right now, including live-action TV shows like The Mandalorian, animated series like Star Wars: The Clone Wars and Star Wars Rebels, all nine Skywalker Saga movies, and Disney's standalone films like Rogue One: A Star Wars Story (2016) and Solo: A Star Wars Story (2018).
Thanks, team!