Following the pivotal Battle of Endor, which occurred in 4 ABY, Mon Mothma formally announced the creation of the New Republic. This declaration signified the culmination of the Alliance to Restore the Republic's evolution into a functioning government.
The concept of declaring a New Republic initially surfaced within Star Wars canon in Daniel Wallace's 2017 reference work, Star Wars: On the Front Lines. Previously, the idea was present in Star Wars Legends through the Heir to the Empire Sourcebook, a 1992 reference volume authored by Bill Slavicsek.