 He described the Yuzhi (), or Niuzhi (), as a people from the north-west who supplied jade to the Chinese from the nearby mountains of Yuzhi () at Gansu.The nomadic tribes of the Yuezhi are documented in Chinese historical accounts, in particular the 2nd–1st century BC "Records of the Great Historian", or "Shiji", by Sima Qian.According to Han accounts, the Yuezhi "were flourishing" during the time of the first great Chinese Qin emperor, but were regularly in conflict with the neighboring Xiongnu tribe to the northeast.