The Kingdom of Barseg functioned as an interstellar power, governing several planets within the Allied Tion sector, notably its primary world Barseg along with Lianna. As one of the Three Allied Kingdoms, it met its end when the Kingdom of Cron incorporated it during the conquests undertaken by the pirate-king known as Xer VIII.
Following the downfall of the empire after Xer's son, Xim the Despot was defeated at the Third Battle of Vontor, the Kingdom of Barseg was re-established. It became one of the successor states arising from the ashes of Xim's empire, and it persisted until its integration into the Galactic Republic in 23,900 BBY.
The final significant war for independence on Lianna against Barseg was spearheaded by the Lianna provinces of Caldara and Berene, ultimately leading to their complete destruction. The Galactic Senate disregarded the situation on Lianna until it seized control of the planet from Barseg in 300 BBY. While it was a part of the Galactic Republic, the kingdom's destiny after 300 BBY remains shrouded in mystery.