In House of the Dragon, we learn a bit more about Valyria, which is now known as Old Valyria. Basically, it’s a 5,000-year-old empire that ruled all of the continent of Essos. Filled with 14 volcanoes and many more dragons, as well as a highly advanced civilization, the people of Valyria rose up in power in ancient times to conquer much of the world, not unlike the real-life Roman Empire.

Many Game of Thrones fans might remember the power of Valyrian steel. This is steel forged during the Valyrian Freehold, of which the methods have since been lost. Some stories claim that the steel was forged with magic spells and dragon fire, but there’s no way to confirm this. The unique steel is one of the few things with the power to kill White Walkers, and Arya actually used a small dagger made of Valyrian steel to kill the Night King and end the war.

House Targaryen was actually a mid or low-level house in comparison to some of the other houses of Old Valyria. While most families were dragonriders, other houses (now extinct) controlled their dragons with sorcery and spells. Eventually, however, Old Valyria fell to the Doom of Valyria, which was referenced in a poem recited by Tyrion Lannister in Game of Thrones as “the Doom.”

The Doom of Valyria was basically a cataclysmic natural disaster, in which all 14 of Valyria’s volcanoes exploded. This burst the land into separate islands, killing all its inhabitants in the process. All the ancient architecture, and even many of the dragons, fell to the Doom of Valyria.

Only two families survived. The first was the Targaryens, who escaped to Dragonstone, just next to Westeros, thanks to Daenys’s prophecy that Valyria would fall to destruction. The other survivors? House Velaryon.