Once the famed guardians of justice in a galaxy harrowed by war and corruption, the Jedi became increasingly distant in the Old Republic's twilight. Many saw them as apathetic. Likewise, disagreements with the Republic over their expansionist policies alienated them from one another.
When the Zygerrian war broke out, the Jedi did not officially answer the call to war, despite the supposedly righteous call to arms against the slavers of Zygerria. There were disagreements, and many Jedi went rogue, following the Republic into battle. After the war, the feud over the the Republic's policies went internal and reached a breaking point. Numerous Jedi were expelled or left voluntarily, signaling the Great Schism. This decision would haunt them years later as the so-called Fallen Fifty returned from exile not as Jedi, but as Sith. Like the war with Zygerria, the Jedi chose a watch-and-see approach, which was a fatal mistake. After the fall of the Republic, the new Sith Empire launched an attack on the Jedi Temple on Tython, with less than a hundred Jedi surviving that day. The handful of Jedi that remain are disorganized and scattered.