The prequel will take place thousands of years before the events of Game of Thrones, which concluded its eight-season run in May

The series, from creators George R.R. Martin and Jane Goldman, will take place thousands of years before the events in Game of Thrones and “chronicles the world’s descent from the golden Age of Heroes into its darkest hour,” according to HBO’s official description.

“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,” the official description continues.

Martin previously told Entertainment Weekly that “Westeros is a very different place” in the prequel, compared to the Westeros fans are familiar with from Game of Thrones.

“There’s no King’s Landing. There’s no Iron Throne. There are no Targaryens — Valyria has hardly begun to rise yet with its dragons and the great empire that it built. We’re dealing with a different and older world and hopefully that will be part of the fun of the series,” he said.

While HBO has not yet confirmed an official title for the series, Martin, 70, said last year that it will be called The Long Night.