The new show in George RR Martin’s epic fantasy world will be set 300 years before the events of TV smash hit “Thrones,” and is based on the book “Fire and Blood.”

“It’s my pleasure to announce we are ordering ‘House of the Dragon’ straight to series for HBO,” Casey Bloys, president of programming, told a Los Angeles launch event for HBO Max.

“It tells the story of House Targaryen and the early days of Westeros.”

The new series will be executive produced by Martin, Ryan Condal and Miguel Sapochnik, who directed “Game of Thrones” episodes including Emmy-winning “Battle of the Bastards.”

HBO Max, WarnerMedia’s new Netflix rival, will launch in the US in May, and will cost US$14.99 per month, it was also revealed.

The platform will feature original shows including a Ridley Scott sci-fi and exclusive rights to “South Park.”

It will offer around 10,000 hours of content at launch, including all 23 seasons of satirical cartoon “South Park” and three new seasons to follow.

The presentation ended with the surprise announcement of “the next great chapter in George’s saga.”

No details of the “Thrones” prequel’s launch date were announced.