The prequel to HBO’s hit series Game of Thrones, House of the Dragon is said to begin production overseas in April. Set 300 years prior to GoT, the prequel will trace the history of House Targaryen. House of the Dragon is one of five prequel ideas HBO has developed. HBO will continue to explore more spinoff ideas. “In terms of the right number, I’d say the number is the shows that are good,” Casey Bloys HBO and HBO Max Chief Content Officer answered, when asked about the number of Game of Thrones successors he’d like to see developed.