Star Wars: 10 Greatest Sith Lords You'll Never Forget
Before Darth Bane the Sith had been a large cult containing numerous Sith Lords and apprentices. However after Bane created the "Rule of two" all of this changed. In previous Sith Empires in-fighting plagued the Dark council as varying Sith Lords jockeyed for power.
Bane saw this as a weakness that needed to be eliminated if the Sith were ever to become powerful again. Thus he created a rule which stated that at any time there may only be a Master and their apprentice. He stated that "Two there should be; no more, no less. One to embody power, the other to crave it."
The apprentices lust for power would ensure that when they were strong enough in the way of the dark side they would kill their own master and then find their own apprentice to continue the cycle.
This earns Bane a spot as he was solely responsible for changing the structure of the Sith order with a rule that later a thousand years until the rule of Darth Sidious.