Valyria was the capital city of the once-great civilization known as the Valyrian Freehold. The city of Valyria is located on the eastern continent of Essos, southeast of the Free Cities, on the Valyrian peninsula, a large peninsula extending southwards into the Summer Sea.

Valyria's power was based on the taming and use of dragons in warfare, which they discovered in the chain of volcanoes known as the Fourteen Fires which were located around their homeland. Using dragons, Valyria destroyed the armies of opposing nations and conquered a large amount of territory in Essos. Its empire, the Valyrian Freehold, extended through much of the modern Free Cities and even onto the island of Dragonstone in the Narrow Sea. However, Valyria never attempted an invasion of Westeros, which was considered a poor backwater. For over 5,000 years, Valyria was the capital of the greatest civilization mankind had ever seen, the heart of an empire that ruled half the known world.

Valyria was destroyed in a catastrophic volcanic event known as the Doom of Valyria, which shattered the Valyrian peninsula, wiped out almost all the dragons in the world and created the much-feared Smoking Sea. The only major family of Valyrian dragonlords to survive the Doom were the Targaryens, who were living on Dragonstone at the time. The Targaryen dragons on their island were the only ones in the entire world to survive the cataclysm. After its fall, the city was commonly referred to as "Old Valyria".