There have been talks for quite some time now about a Game of Thrones prequel series. Before the show even ended they were talking about making prequels, with several in the works. Well, we already know a few of those prequels got scrapped, but it appears one with promise is moving forward. Entertainment Weekly confirms that casting for House of the Dragon, the prequel based around the Targaryens, is underway. 

House of the Dragon will be based on the George R.R. Martin novel Fire & Blood, which takes place 300 years before Thrones. This makes it hard for showrunners and writers to mess up the ending... because it is already laid out for them in the book. The show is expected to show the events that led up to the legendary Targaryen civil war, called "Dance of the Dragons." This war is essentially what caused them to destroy their home and migrate west, where they conquered Westeros with their dragons. The idea of destroying your home, and migrating to the western side of the world to take over, bears similarities to the European expansion. The pilot and additional episodes will be directed by Miguel Sapochnik, who was behind "The Battle of the Bastards" and "The Long Night."