BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
Fueled by vengeance and rage, the newly reunited brothers Darth Maul and Savage Opress spread terror and violence. As they forcibly recruit criminals from the darkest corners of the Outer Rim to join their army, the brothers begin to consolidate their new criminal empire in an effort to bring out Darth Maul’s most hated enemy: Obi-Wan Kenobi.