The Expansionist Era, also known as the Expansion Period or the Galactic Expansion Era, was the term given to the years after the Galactic Republic formed, when transit between the Core Worlds was opened up by the newly-developed hyperdrive, and during the early expansion of the Republic. Also, the Tion Hegemony, at this time, was a proud civilization, and most of the worlds of the Allied Tion sector were settled.
The Corellian Run is mapped, ensuring the economic dominance of Corellia in the forming Republic; the Corellian Run forms the southern border of the Slice.
Republic scouts make contact with the Jedi Order on Ossus, and Jedi MasterHaune Tiar accompanies the scouts back to the Republic. After conferring for several weeks, the Order pledge themselves to the Republic's service.
With the development of the hyperdrive, Queen Rana allows for a wave of colonization to embark from Duros; one of the colony worlds is the planet Neimoidia, which is colonized by a group of Duros led by Chla C'cHaan. (Approximate date)
The Jedi Sar Agorn takes on a Padawan in Cope Shykrill, but Shykrill falls to the dark side of the Force and is struck down. (Approximate date)
The First Great Schism erupts in the Core Worlds between the Jedi Order and the Legions of Lettow, members of the Jedi Order who seek to use the dark side against the Order's wishes. The Legions' leader Xendor originally asked for permission to create an academy for the study of Force techniques outlawed by the Jedi, and after their refusal he founded the Legions on Lettow—prompting the Order to declare war on them.
The Schism sees Xendor's death at Columus, and the conflict ends not long afterwards as the Order invaded Lettow.
The Tionese War begins: the Tionese unite as the Honorable Union of Desevro & Tion and attack the Republic, storming down the Perlemian. The Republic begins producing warships at Core shipyards, but the Tionese push into the heart of the Republic and bomb numerous worlds. The Republic ultimately repels the Tionese with a desperate counterattack by numerous Core systems, sparking a series of offensives and counteroffensives that last around a century.