Tyria is a former city of the Valyrian Freehold. It was laid waste in the Doom of Valyria. Its ruins are now located on the same island as the ruins of Valyria itself, across the Smoking Sea from Oros.
In the books
In the A Song of Ice and Fire novels, Tyria is connected by a Valyrian road to the ruins of the capital city of Valyria.
- Tyria at A Wiki of Ice and Fire (spoilers from the books)