It is the only moon of Yavin that is suitable to live on and served as the Rebel Alliance's secret base during the events of A New Hope.
It was here the momentous Battle of Yavin IV took place, a small Rebel strike forces were able to destroy the Galactic Empire's dreaded Death Star. It's destruction was made possible by Luke Skywalker who's piloting skills and use of the force, was able to strike at the Death Star's weak point destroying it. This marked as one of the greatest victories of the Rebel Alliance. However the Empire responded swiftly and sent a massive strike force to Yavin IV, lead by Darth Vader himself the Empire destroyed the rebel base, forcing the Alliance to flee.
Long before the Galactic Civil War Yavin IV was controlled by the ancient Sith Lord Naga Sadow. Naga Sadow retreated into Yavin IV after his defeat in the Great Hyperspace War by the Galactic Republic. There he preformed Sith expriments on his Massasi warriors turning them into primitive red skinned mutants, and used them as his slaves. The Massasi worshiped Naga Sadow as a god building various temples in his honor, Naga Sadow later entombed himself in a sarcophagus and placed in a coma like state, while his Massasi warriors guarded his tomb, the Sith lord waited for some one to come and take up the legacy of the Sith.
A fallen Jedi named Freedon Nadd came to Yavin IV to seek out the secrets of the Sith. After defeating the Massasi who attacked him he found the tomb of Naga Sadow and awaken the spirit of the Sith lord. Freedon Nadd was able to master Sith magic from Sadows teachings, but after learning everything he could from him he destroyed the Sith lords spirit and proclaimed himself as the new Dark Lord of the Sith.
Another fallen Jedi Exar Kun came to Yavin IV under the guidance of the ghost of Feedon Nadd, he was captured by the Massasi and was about to be eaten by a Sith wyrm, Kun embraced the dark side and killed the beast, he then cast aside Feedon Nadds ghost and took control over the Massasi warriors, and set about to conquer the galaxy as a Sith Lord. In the war that followed Exar Kun was driven back to Yavin IV by the Jedi, in a last ditch effort to escape Exar Kun planned a ritual that would allow his spirit to seperate from his body and travel the across the galaxy. He then sacrificed his remaining Massasi warriors to accomplish this ritual, but his spirit was then trapped in the ruins of the Massasi temple.