While the Sith are usually thought of as being synonymous with the Dark Side of the Force, they are actually just one faction of Dark Side users across the Star Wars galaxy–and one of the latest contributions to Star Wars lore explains exactly why the Sith are the most powerful.
The Sith were first introduced in Star Wars’ original trilogy, with Darth Vader being the first one shown and his master, Darth Sidious, following soon after. Without explicitly stating as such, fans were already exposed to the Sith Rule of Two upon the Sith’s debut–a rule that dictates there be no more than two Sith at a time, a master and an apprentice. This rule was established by Darth Bane long before the time frame of the films due to the fact that the Sith–before this rule was made–just kept killing each other. Before the Sith Rule of Two, there were armies of Sith spread out across the cosmos and their goal was to exterminate the ever-growing Jedi Order as well as any other Dark Side cult that wasn’t associated with the Sith.
In Star Wars: Doctor Aphra #24 by Alyssa Wong and Minkyu Jung, the morally ambiguous space explorer Doctor Aphra has in her possession an artifact known as the Spark Eternal–and it has effectively taken control of her body. The Spark Eternal is artificial intelligence that links all life forms, both artificial and organic, and also supplies its user with Force-like abilities. The Spark was created long ago by Miril, who was the leader of a Dark Side cult known as the Ascendant. While the Ascendant practically worshiped the Dark Side, they didn’t actually have access to the Force, so Miril created the Spark Eternal which acted as the Force’s artificial equivalent. When Doctor Aphra was consumed by the Spark, her mind was propelled through some key events in the past–both from her memory, and from the memory of the Spark’s creator, Miril.
One of the memories Doctor Aphra is thrown into is that of the Sith’s attack on the Ascendent long before the Sith Rule of Two was established. This is incredibly insightful as to why the Sith seem to be the only group of Dark Side wielders fans are made aware of despite the fact that there were many more out there–the Sith simply killed them. Not only that, but because the Sith were so protective over their Dark Side sovereignty, anyone who heard the call of the Dark Side immediately joined the Sith rather than joining some other cult that would inevitably be wiped out by the Sith. However, that isn’t to say there weren’t some Dark Side cults who survived this particular purge.
While the Ascendent were all but obliterated by the Sith–with the Spark Eternal practically being the last remnant of their order–there were other Dark Side cults who remained and even continued to practice well into the age of the Empire. One such cult was introduced in Star Wars: The Clone Wars, the Nightsisters–and they were responsible for unlocking Savage Opress’ access to the Dark Side and also for restoring Darth Maul to his former glory. Another cult that actually outlasted the Sith (to some extent) is the Knights of Ren who were originally a Dark Side-worshiping gang of roving anarchists. However, when Kylo Ren took control of the Knights of Ren, he inadvertently joined them to the Sith as his master was secretly Emperor Palpatine–a man who proclaimed in Star Wars: Episode IX – Rise of Skywalker that he was “all the Sith”. So, even with a few outliers, the Sith effectively eradicated every other Dark Side cult, which led to them gaining more followers and increasing their influence over the galaxy–proving why the Sith are Star Wars’ most powerful Dark Side cult.