The writer, who's also serving as an executive producer on Jane Goldman's pilot, said as much when breaking down five quick facts about the prequel in an Entertainment Weekly chat published Tuesday.
"Obviously the White Walkers are here—or as they’re called in my books, The Others—and that will be an aspect of it," Martin added of the dragons-preceding tale. "There are things like direwolves and mammoths." Martin was also generous enough to reveal that fans will get a look at as many as 100 "petty kingdoms" thanks to where the series falls in general Thrones history, with Westeros being teased as likely being even more chaos-prone than it was in the original HBO series.
Other intel from Martin includes confirmation that the Lannisters, at least for now, will not be seen in the prequel, as well as some informed theorizing on a possible title (The Longest Night) and an assessment on how the prequel will follow the ensemble-focused approach of its predecessor.
"We don't have leads so much as a large ensemble cast," Martin said, noting that he's hesitant to ever use the "lead" qualifier in general.
We'll see how much of this holds true when the as-yet-untitled prequel series arrives (presumably by 2021). The pilot is directed by SJ Clarkson and counts Naomi Watts and Josh Whitehouse among its cast. Filming, per reports in June, has already quietly kicked off in Northern Ireland.