According to a reconstruction by G.H. Luce, the millennium-old Pyu realm came crashing down under repeated attacks by the Nanzhao Kingdom of Yunnan between the 750s and 830s AD. Like that of the Pyu, the original home of Burmans prior to Yunnan is believed to be in present-day Qinghai and Gansu provinces. After the Nanzhao attacks had greatly weakened the Pyu city-states, large numbers of Burman warriors and their families "first" entered the Pyu realm in the 830s and 840s, and settled at the confluence of the Irrawaddy and Chindwin rivers, perhaps to help the Nanzhao pacify the surrounding countryside. Indeed, the naming system of the early Pagan kings—Pyusawhti and his descendants for six generations—was identical to that of the Nanzhao kings where the last name of the father became the first name of the son. The chronicles date these early kings to between the 2nd and 5th centuries AD, scholars to between the 8th and 10th centuries CE. (A minority view led by Htin Aung contends that the arrival of Burmans may have been a few centuries earlier, perhaps the early 7th century. The earliest human settlement at Pagan is radiocarbon dated to c. 650 AD. But evidence is inconclusive to prove that it was specifically a Burman (and not just another Pyu) settlement.)