WARNING: The following contains spoilers for Star Wars #7, by Charles Soule, Ramon Rosanas, Rachelle Rosenberg, and Clayton Cowles, on sale now.
In the Star Wars galaxy, when it comes to disorder it's usually the Rebel Alliance that is the cause of it if you believe in what the Empire says. Late on, the First Order would aim the blame toward the Resistance, while the Jedi would mention the Sith, and so on. However, one's man terrorist is another man's freedom fighter so it all depends on perspective and who is saying what.
Marvel's Star Wars #7 sheds some brief, but key, insight into the galaxy's new anarchists, the Nihil, and this group could be the most chaotic one yet as their true motives and why they really exist is shrouded in secrecy.
It comes to light when Governor Tarkin is seen trying to find the most suitable person for an assignment to hunt down the warlord and dissident, Burnium Ro. This all occurs with the Death Star in operation during Star Wars: A New Hope and with Ellian Zahra as Tarkin's most promising student, being assigned the job. He even gives her his corvette, the Carrion Spike, as he knows she'll need firepower. The reason being is Ro has been using symbols and philosophies associated with the Nihil terrorist cell and Tarkin wants him snuffed out for sedition.
He hates the havoc this has caused and eager to please him, Zahra uses the ship and some probe droids to mercilessly blows Ro's base up on Ikkrukk. However, Tarkin chides her for not bringing back his head, as she should have known she assassinated a decoy instead. He's furious, playing a recording of Ro, who makes it clear he's an untouchable symbol. As Ro sends this message, there are still no clues as to who this movement is.
It can't be the Rebels as they have never mentioned the Nihil, plus in the High Republic era, the Nihil razed planets as enemies of the Jedi. So if they were fighting the Jedi, it would stand to reason they'd be no friends of the Rebels later on. It could be that they evolved into pseudo-allies along the lines of the Cloud Riders, traders, marauders, and smugglers, seen in Solo: A Star Wars Story. But again, if this were the case, Tarkin would have mentioned it rather than treated them as a separate entity.
So right now, the Nihil is a dirty, self-serving rogue faction, which more will be revealed of when the High Republic comics and novels are published. Their backstory years before all this drama occurred, how they went to war as "space Vikings" with the Jedi, and what remnants were left behind to work with Ro will all be revealed.
That said, a group that Tarkin hates and possibly fears, and one who wanted the Jedi dead is definitely not to be taken lightly. And as Ro hinted, these unpredictable terrorists are in the shadows in numbers, waiting for the right time to pounce, and it seems they're targeting everyone.
Star Wars: The High Republic begins Jan. 5 with Star Wars: The High Republic -- Light of the Jedi, by Charles Soule.