HBO has announced that the second in a series of planned Game of Thrones prequels will center on the Targaryen family. Per Deadline, the series is about to receive a pilot order. The show comes from A Song of Ice and Fire author and Game of Thrones executive producer George R.R. Martin, as well as Colony co-creater Ryan Condal, who will write the show’s pilot. The unnamed project will be based on Martin’s book Fire & Blood, which was released late last year with the tagline: “300 Years Before a Game of Thrones, Dragons ruled Westeros.”

Martin’s new novel chronicles how the Targaryen came to land in Westeros, the continent where Game of Thrones is primarily set.  Armed with dragons and a propensity toward ruthlessness, the family takes control of the entire landmass under the leadership of the aptly named Aegon the Conqueror. In a story that spans generations, the Targaryens face a number of challenges to their power, including a civil war, before their dynasty is finally ended by a revolt that ultimately sets the table for the Game of Thrones series. As a direct result of that war, Daenerys Targaryen, played by Emilia Clarke, is one of the few surviving Targaryens at the beginning of GoT.

The Targaryen series represents the second of five prequel concepts that were initially considered after Game of Thrones’s finale. In a blog post in May, Martin alluded to the status of those prequels, writing, “We have had five different Game of Thrones successor shows in development . . . at HBO, and three of them are still moving forward nicely.”

Another prequel, set thousands of years before GoT, has already filmed its pilot and is currently in post production. Written by Jane Goldman and starring Naomi Watts and Josh Whitehouse, that series is set to depict a narrowly averted cataclysm involving the original show’s zombie-esque White Walkers. Per HBO, “The series chronicles the world’s descent from the golden Age of Heroes into its darkest hour. From the horrifying secrets of Westeros’s history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend, only one thing is for sure: It’s not the story we think we know.”

Game of Thrones showrunners David Benioff and D.B. Weiss are attached to both projects as executive producers due to a pre-existing deal with HBO. Such a distinction will be in name only, however, as both have signed a massive overall deal with Netflix, ending their relationship with HBO as a result. As such, they will have no creative input on the series.

HBO has yet to announce a timetable for either series’ release.