The Star Wars timeline uses the Battle of Yavin as its main distinction, separating it into Bby (Before Battle of Yavin) and Aby (After Battle of Yavin). In-universe historians debated other events to base the calendar on, such as the Empire's formation or the Battle of Endor, but the Battle of Yavin won out due to its symbolic importance and precise timing. The choice of the Battle of Yavin as the calendar's dividing point centers the Rebel Alliance and the people of the galaxy, rather than the Empire and Palpatine.

The Star Wars timeline and calendar has always been a bit confusing, but there's now a canon explanation for using Bby and Aby as its main distinction. The Star Wars timeline uses a peculiar dating system, one that resembles the real-world equivalent of Bce and Ce, where a single event separated the halves of the calendar. The Star Wars version...