Anuradhapura

State · 291 BCE – 1017 CE · at its largest around 291 BCE

Kingdom of Sri Lanka with its capital at Anuradhapura, where Buddhism was established and which lasted until the Chola invasion of the early 11th century.

On its lands while it lasted

• Buddhism reaches Sri Lanka (c. 250 BCE): According to Sri Lankan chronicles, Ashoka's son Mahinda brought Theravada Buddhism to the court of Anuradhapura in the 3rd century BCE.
• Sigiriya (c. 477 CE): Rock fortress and palace in Sri Lanka built by King Kashyapa I in the late 5th century, famous for its frescoes and lion gateway.

More on Wikipedia.