The Galactic Jedi Republic, also known as the Galactic Republic, the Great Jedi Order or simply the Republic, was a Federal Republic under the control of the Jedi senate and it was guaranteeing the freedom and liberty of all beings under its reign. Eventually, the 3rd Mandalorian Crusaders brought it to its knees and it was reorganized into local independent systems under local governors.
The Republic, as the tale tells, was formed from a confederacy of worlds, known as the Human Core, which consisted of almost 100 worlds. This confederacy was formed thousands of years before the battle of Yavin, and was a beginning of galactic rule. It is the accepted successor to the former glorious WuuRumm Empire, which dominated the galaxy before it. After the formation of this confederacy, there were many wars, and many battles were fought. These wars are known as Confederation Wars, and were eventually won by Coruscant. Several centuries after the end of these wars, the confederacy was united into one political-economical-social division which evolved eventually in to this Republic.
Golden Age of the Jedi
During the Golden Age of the Jedi, the Republic prospered, discovering much of the known galaxy, and creating many trade routs throughout the galaxy. During this age, the Republic had no rivals, and enjoyed a dozen millenniums of unchallenged galactic dominance. The Jedi, indeed brought peace and liberty wherever they reached, and the citizens of the Republic enjoyed wealth and happiness during its reign. This era eventually came to an end when the galaxy entered the Jedi-Sith Crisis, a cold war which lasted for almost two millenniums.
After several millenniums of peace and growth, the Republic discovered a new rising empire, known as the Trico-Frost Sith Empire, which declared war on the Republic(8,154 BBY - 6,358 BBY). Though the actual war ended after a dozen years, the real crisis, continued for over two millenniums, and the outcome was eventual collapse of the Sith empire. This crisis had devastating effects on the republic, it is said that almost 15.4 trillion creatures of all species were killed in these wars, almost 40% of the known galactic population back then. The Republic had two millenniums to reconstruct itself until an outbreak of another crisis.
In the year 4,056 BBY, a human male was born in Onderon, named Omuk Frost. The man was force sensitive as a baby, and was taken for Jedi training in the Jedi Temple on Coruscant. He was a very powerful Jedi and a successful student, until he was sent to a mission which changed his destiny, as well as the Republic's. On his mission there he discovered his Sith ancestry, and began his training as a Sith Lord. After three years of training, he emerged and took over the shattered remnants of his ancestor's empire, and united the Mandalorian clans and the Sith under his reign.
Before Omuk Frost was sent on his mission, a crisis began against the Mandalorians. the crisis began when the Mandalorians began to arm their armies and build massive ships. Eventually, the crisis reached an end in the signing of a treaty which will guarantee the safety of the Republic if the Mandalorians be allowed to construct their warships and recruit their troopers for protection against pirates raiding their home planet
Fragmentation and Eventual Dissolution
After taking control over the Mandalorians, Darth Admer declared war against the republic, in which it received devastating blows. After eight years of a devastating war, the Republic collapsed in to shattered remnants which were governed by local Jedi governors. The Union was declared, and another war evolved. This war, resulted in the final dissolution of the remnants of the once glorious Galactic Jedi Republic in 3,072 BBY.