George R.R. Martin, author of the Song of Ice and Fire novel series on which the series Game of Thrones is based (as well as the novella Nightflyers on which the new Syfy series is based) divulged a few details about the upcoming Game of Thrones prequel in an interview with the New York Times, probably much to HBO's chagrin.
Martin said that preproduction on the pilot episode of The Long Night (the unofficial title he insists on using even though HBO has asked him not to) is coming along, and that writer Jane Goldman has built out the ancient world of the "Age of Heroes" and the arrival of the White Walkers based on the few details scattered throughout his novels. "Jane had to create the characters, the settings and some of the events, and we had to look at everything that was said and say, 'ok, here's what was said at this point, we need to make it consistent to that,'" Martin said. His role on the pilot is in more of an advisory capacity, while Goldman is doing the heavy lifting.
Then he revealed some pretty significant stuff about what to expect: "It's set thousands of years before Game of Thrones. King's Landing does not exist. The Iron Throne does not exist. There are no dragons there." He won't say if there will be ice spiders of the kind described in Old Nan's story. (I wouldn't be surprised if ice spiders show up in Game of Thrones Season 8, actually.)
HBO's official description of the Naomi Watts-starring pilot is that it "chronicles the world's descent from the golden Age of Heroes into its darkest hour. And only one thing is for sure: from the horrifying secrets of Westeros' history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend - it's not the story we think we know."
Martin also said that he wants to do a show called Spear Carriers that would focus on background characters with ordinary jobs instead of royalty, but HBO isn't interested, probably because that's not actually a good idea. The premise would quickly exhaust itself as the characters get swept up in the grand, regal intrigue that's the truly compelling part of Game of Thrones.
Game of Thrones Season 8 will premiere in April 2019.