Time of Events = Around 25,000 Years B.S.W.N.H, to about 35 Years B.S.W.N.H
Not many people know what happened before the original Trilogy, but we do know a few details about the first three episodes of the STAR WARS Saga.
We know things like: Darth Vader was once a Jedi Knight by the name of, Anakin Skywalker, Obi-Wan Kenobi was Anakin's mentor, Yoda was Obi-Wan's mentor and a few other small mattered details.
During this era we know that the Jedi Knights were the major source of defense in the STAR WARS galaxy, reigning with their major source of power, the FORCE.
The FORCE is an energy field generated by all living things. It is all around our universe, penetrating all ( STAR WARS speaking of course). The FORCE was their teacher and was it was also their weapon and religion.
The Jedi Knights fought to protect the Old Republic and just warded off the enemies but their fall came with the Clone Wars. We don't know much about these wars but, we do know that at the end the Empire was in major power with, the Emperor Palaptine to thank. The emperor ahd wiped out the Jedi Academy, took Anakin Skywalker and made him: Darth Vader, and sent a few Generals into hideout like: Yoda - who went to Dagobah and Obi-Wan Kenobi - who went to Tatooine.
Basically, this era was the birth of the Empire and the downfall of
the Republic to become the small, yet powerful, Rebel Alliance.