 It has been, in particular, the basis of theories that the Ashina – the royal clan of the Göktürk Turks – originated amongst the Wusun.In 162 BC, the Yuezhi suffered a further, more decisive defeat at the hands of the Xiongnu and retreated from Gansu.According to Zhang Qian, the Yuezhi fragmented and most fled westward into the Ili river valley.