The First Order origins have been revealed in The Star Wars Book. Star Wars fans knew a little bit about the First Order, thanks to the sequel trilogy, which began with 2015's The Force Awakens. However, the movies all left a lot of information out, which sent some hardcore fans looking into comic books, novels, and video games for more official canon information. When it comes to the First Order, and even Snoke, fans didn't really have any concrete answers until now.
The Star Wars Book is written by Pablo Hidalgo, Cole Horton, and Dan Zehr. There's a section on the First Order that touches up on what most Star Wars fans already knew. "We know that the military might of the First Order was built up in the Unknown Regions by the escaping Imperial leadership in the decades after the Battle of Jakku," according to the book. However, it also reveals that "The First Order also had its start inside the New Republic."
As it turns out, agents of the First Order helped push for a stronger centralized role of the New Republic government. This ended up causing "a political stalemate, forcing systems that fear losing control of their autonomy to break away from the New Republic - in a coalition called the First Order." Had the remaining members of the Empire not fled to the Unknown Regions, the First Order would never have been able to mobilize. In The Force Awakens, Kylo Ren says, "A stability that existed under the Empire, was reduced to anarchy by the Rebellion, was inherited in turn by the so-called Republic, and will be restored by us. Future historians will look upon this as the time when a strong hand brought the rule of law back to civilization."
Star Wars Book also reveals that Snoke was a vessel for Emperor Palpatine to control, which was also hinted at in The Rise of Skywalker. However, the book indicates that Snoke had free will, even though his ultimate goals were still controlled by Palpatine. Star Wars fans were a bit letdown by Snoke after he was built up in The Force Awakens, though it's finally nice to have some clarity about why he was created in the first place, allowing for Palpatine to sidestep the traditional dark side apprentice slaying his master to ascend.
Star Wars fans are getting a tease of what life was like after the Empire fell in Return of the Jedi in The Mandalorian. The show takes place five years after the last installment in the original trilogy, which is when the surviving members of the Empire were planning a return with the Republic in the Unknown Regions. Moff Gideon is a remnant of the Empire in the hit series, and his role is believed to be greatly expanded in the second season. You can head over to Pengun Random House for more information on the Star Wars book.