What was the Doom of Valyria?

What was Valyria before the Doom?

Valyria was the home of the Freehold, a power built on dragons and on the families who rode them. Its smiths made the steel that still carries the name, and its spells, its learning and its records were lost with it. The Targaryens were one of its dragonlord families, which is why everything about their later history in Westeros traces back to it.

For the story, Valyria matters less as a place than as a loss. Almost everything precious in the world of the novels, from the finest blades to half-remembered magic, is a remnant of something the Freehold had and nobody has since. That gives the setting its particular mood: a present lived in the ruins of a past that was more powerful and is not coming back.

What happened, and why does nobody know?

The histories describe the Doom as a cataclysm whose nature they cannot specify. It broke the Valyrian peninsula into many smaller islands and left a sea of smoke between them, and in the same stroke it destroyed the knowledge, the spells and the records that might have explained it. A civilisation that could have recorded its own end did not survive to do so.

That uncertainty is a deliberate choice of the books, and a useful one. A catastrophe with a known cause would be a historical event; one without a cause becomes a warning that can be read many ways, as punishment, as accident, as the price of power. Different characters can read it in different ways, and the novels leave each of them free to be wrong.

How did the Targaryens survive it?

Through a dream. Twelve years before the Doom, Daenys Targaryen, the unmarried daughter of the family's lord, dreamed of Valyria's destruction, and the family moved to the island of Dragonstone. When the Doom came, they were out of its reach, with their dragons. That move is why a single exiled family later had the means to conquer a continent. It is the hinge of the family's whole history: without it there is no Conquest, no Iron Throne and no Daenerys.

The dream also set a pattern the family never shook off. Later Targaryens took their own dreams and prophecies seriously because one dream had once saved them all, and the series returns to that habit more than once. In House of the Dragon a dream handed down from Aegon the Conqueror frames the whole succession, an echo of the dream of Daenys that had brought the family to Westeros in the first place.

What remains of Valyria in the story?

Ruins and steel. In Game of Thrones' fifth season, first shown in 2015, Tyrion Lannister and Jorah Mormont pass through its ruins, where they are attacked by the stone men. It is one of the few times the series lets the audience see the old empire, and it shows a dead place rather than a lost glory.

The steel matters more to the plot. Valyrian steel blades survive from before the Doom and cannot be made anew, because the method died with the Freehold; a few smiths can reforge an existing blade, but nobody can forge a new one. In the show that rarity becomes vital, because Valyrian steel is one of the few weapons that can destroy a White Walker. The empire that fell centuries ago supplies the tools for the last war.