During the late 2nd century BCE, Emperor Wu of Han (r. 141 BCE – 87 BCE) was interested in extending contact with Dayuan (Fergana), following the reports of it by the Chinese envoy, Zhang Qian. However, according to Chinese sources, Han envoys to Fergana were harassed by Loulan and the kingdom of Gushi (or Jushi). Consequently, in 108 BCE, Loulan was attacked by a Han force led by Zhao Ponu (趙破奴) and its king captured, after which Loulan agreed to pay a tribute to Han China. The Xiongnu, on hearing of these events, also attacked Loulan. The king of Loulan therefore elected to send one of his sons as a hostage to the Xiongnu and another to the Han court. Due to Loulan's association with the Xiongnu, the "Book of Han" records: