The alliance was founded in 1,340 ABY, when the planetary governments of several systems in the Core Worlds signed a treaty on Coruscant. It was widely believed, at this point in galactic history, that a single galactic government could not successfully rule. This idea was popular due to the fragmentation and destruction of the Galactic Union. When the dust settled after the GU Civil War, it was decided that a number of interdependent regional governments would be established.
By 1,380 ABY, the new idea was generally succeeding. The CSA was joined by the Bothan League, Bespin Treaty Association, Vawta Union and the Muun Federation. Unlike previous galactic governments, in which the Jedi Order was a branch of the government, the Order acted as its own semi-independent entity. One grandmaster was chosen to oversee Jedi affairs and a temple was established on Ruusan. Individual Jedi could take citizenship and other titles in any of the alliances, while still pledging loyalty to the Order itself. Notable Jedi within the CSA included Marco Klval and Jihmy Gon-Dorff, who were generals in the CSA Army.
Conflict with the Bothan League
In 1,400 ABY, the Core Systems Alliance established an official partnership with the Bespin Treaty Association. The BTA would send non-voting representatives to the CSA Senate and vice-versa. While in reality this was done to increase productivity and interplanetary trade, Chancellor Lopp Fey'la of the Bothan League saw the partnership as an opportunity to increase his own power. Claiming that the partnership was part of CSA plot to become the dominant galactic government, he began preparation for war. Allying with the Muun Federation, Fey'la built up his military forces and developed plans for an invasion of Core Space. Aware of the Bothan Threat, President Jammi Crane ordered a preemptive attack on the Bothans. The war had begun.
The CSA in the Bothan War
The CSA would be the dominant faction in the Bothan War, fighting on two fronts, beginning in the year 1,402 ABY. It gained a number of allies during the war and while the Core was still the major combatant, the contributions from the Bespin Treaty Association, Mon Calamari, Kashyyyk system and Mandalorians would prove to be very beneficial. By 1,405 ABY, the war had concluded in a total victory for President Crane and his allies throughout the galaxy.
The Universal Republic
At the conclusion of the war, a new government, dubbed the Universal Republic, was founded. Initially, the body loosely allied the signers of the Treaty of Kooriva, the document that ended the Bothan War. This included all the major players in the war, but President Crane hoped to also include the rest of the galaxy and some of the members of the other smaller galaxies in the near future.