To be sure, the Pyu and their culture did not disappear just because 3000 of them were taken away. The size of the Pyu realm and its many walled cities throughout the land indicates a population many times over. Indeed, no firm indications at Sri Ksetra or at any other Pyu site exist to suggest a violent overthrow. It is more likely that these raids significantly weakened the Pyu states, enabling the Burmans to move into Pyu territories. At any rate, evidence shows that the actual pace of Burman migration into the Pyu realm was gradual. Radiocarbon dating shows that human activity existed until c. 870 at Halin, the subject of the 832 Nanzhao raid. The Burmese chronicles claim the Burmans founded the fortified city of Pagan (Bagan) in 849 but the oldest radiocarbon dated evidence at Pagan (old walls) points to 980 CE while the main walls point to circa 1020 CE, just 24 years earlier than the beginning of the reign of Anawrahta, the founder of Pagan Empire.