It was a long-lasting civilisation that lasted nearly a millennium to the early 9th century until a new group of "swift horsemen" from the north, the (Mranma) (Burmans) of the Nanzhao Kingdom entered the upper Irrawaddy valley through a series of raids. According to the Tang Dynasty chronicles, the Nanzhao began their raids of Upper Burma starting as early as 754 or 760. By 763, the Nanzhao king Ko-lo-feng had conquered the upper Irrawaddy Valley. Nanzhao raids intensified in the 9th century, with the Nanzhao raiding in 800–802, and again in 808–809. Finally, according to the Chinese, in 832, the Nanzhao warriors overran the Pyu country, and took away 3000 Pyu prisoners from Halin. (In 835, the Chinese records say the Nanzhao also raided a state, generally identified by some but not universally accepted to be a Pyu state.)