All this talk of different clans of Jedi has got me thinking...maybe this is the new thing that the prequels should have brought to the table.
The way it looks in my head is this...
It is the year 25 BBY, just before the outbreak of the Second Clone War. The Republic is still reeling from its narrow victory against the short-lived Mandalorian Sovereignty, a militant state that used revolutionary new cloning technology to bolster the ranks of its armies. It was thanks only to the intervention of the Jedi Knights that total destruction of the Republic was avoided.
But victory over the Mandalorians came at a price. In their determination to defeat such a persistent and dangerous foe, the Jedi clans known as the "Knights" and the "Masters" discovered that there was a "dark side" of the Force. Some of these rogue Jedi Knights seceded from the order and become the dreaded "Sith Barons". These lightsaber-wielding warriors came to be feared across the galaxy. They practiced the use of the Dark Side as the ultimate expression of anger and hate, the only two things that gave them any power.
Among these traitorous Sith Barons was Anakin Skywalker, who took on the ancient name Darth Vader after his betrayal of the Jedi Knights.
Only one Jedi Master went rogue as a result of the First Clone War. His name was Palpatine. Unlike his more direct Baron counterparts, Palpatine decided that the path to total galactic domination lay in subtlety and manipulation. He decided that one day he would rule the galaxy, but first he needed to convince the public that the Jedi were unworthy to serve as its protectors.
Vader's conversion from Sith Baron to Sith Lord would mark a turning point not just in the life of Anakin Skywalker, but in the history of the entire galaxy.
And so the dark times began.