Evidence shows that the actual pace of Burman migration into the Pyu realm was gradual. Indeed, no firm indications have been found at Sri Ksetra or at any other Pyu site to suggest a violent overthrow. Radiocarbon dating shows that human activity existed until c. 870 at Halin, the Pyu city reportedly destroyed by an 832 Nanzhao raid. The region of Pagan received waves of Burman settlements in the mid-to-late 9th century, and perhaps well into the 10th century. Though "Hmannan" states that Pagan was "fortified" in 849—or more accurately, 876 after the "Hmannan" dates are adjusted to King Anawrahta's inscriptionally verified accession date of 1044—the chronicle reported date is likely the date of foundation, not fortification. Radiocarbon dating of Pagan's walls points to c. 980 at the earliest. (If an earlier fortification did exist, it must have been constructed using less durable materials such as mud.) Likewise, inscriptional evidence of the earliest Pagan kings points to 956. The earliest mention of Pagan in external sources occurs in Song Chinese records, which report that envoys from Pagan visited the Song capital Bianjing in 1004. Cham and Mon inscriptions first mentioned Pagan in 1050 and 1093, respectively.