Wookieepedia Details: Yavin 4 on Wookieepedia
"Great events happened here on Yavin 4. You can get a real sense of history."
Yavin 4 was one of three habitable moons orbiting the gas giant Yavin. It was mainly covered in jungle and rainforest, and despite being remote, it played an important role in galactic events, both in canonical history, and the events of Jedi vs Sith, as the site of the Yavin IV Jedi Praxeum.
Pre-Jedi Vs Sith
The planet was the site of the Battle of Yavin, which was judged to be so critical it formed the reference point of the galaxy's date system. For more information, see Yavin's History on Wookieepedia
Jedi vs Sith
Ander Tagira's Academy
Main Article: Yavin IV Jedi Praxeum
The Jedi academy was reformed sometime after the conclusion of the Yuuzhan Vong War, with the Great Temple rebuilt under the instructions Jedi Master Ander Tagira, and quickly developed into a large and well known establishment, having a vast number of political and military allies and enemies. Ander Tagira departed the Praxeum on a semi-permanent basis some years after it's founding.
With the departure of Ander Tagira, the academy went through a phase of restructuring, as the Jedi Masters of the Praxeum's council reformed the Administrative structure.