Kingdom of Polonnaruwa

The Kingdom of Polonnaruwa (පොළොන්නරුව රාජධානිය) was the Sinhalese kingdom that expanded across the island of Sri Lanka from 1070 until 1232. The kingdom unified the island and started expanding its overseas influence during the reign of Parakramabahu the Great.

Buddhism had been suppressed in the country during the Chola rule, where precedence was given to Saivite Hinduism.

Buddhism was revived in the country during Polonnaruwa era, becoming the main religion. The primary form of Buddhism practiced in the Polonnaruwa kingdom was the orthodox school of Theravada Buddhism. The Polonnaruwa monarchs enjoyed the exchange of religious jewels and other expensive items with the Theravada Buddhist kings of Siam, Burma, and Kampuchea.

Further reading

Kingdom of Polonnaruwa, Wikipedia