The Doom of Valyria was the catastrophic destruction of the ancient Valyrian Freehold, likely caused by the simultaneous eruption of the Fourteen Flames, massive earthquakes, and a tsunami that shattered the peninsula and killed most of its people and dragons.

What happened

Valyria was the greatest power in that world before it collapsed in a single, world-changing disaster. The event was so severe that the land was broken apart, the sea flooded in, and the area became the deadly Smoking Sea.

Why it matters

The Doom ended Valyria’s empire and wiped out almost all of its knowledge, wealth, and dragonlords. It also left House Targaryen as one of the few surviving Valyrian bloodlines, which is why they became so important later in Westeros.

In plain terms

Think of it as a civilization-ending volcanic apocalypse: one day the most powerful empire in the region existed, and shortly after, it was gone.