On Yuan Chwang's Travels in India, 629–645 A.D. v2.c26.s1.9

v2.c26.s1.9

Beyond the desert, he reached I-gu, the capital of a principality subordinate to the kingdom of Kao-ch'ang, the exact position of which apparently has not been determined. Yuan-chwang, who had intended to travel by the northern route past Kagan-Stūpa, the modern Bishbalik or Pei-t'ing, near Gu-chen (Gutchen), to the north of Turfan, was compelled to change his plans in deference to peremptory orders of Kü-wēn-tai (Khio-wen-t'ai, or Kü-ka), the powerful Turkī king of Kao-ch'ang, who insisted on receiving a visit from the pilgrim. A journey of six days through the desert from I-gu brought Yuan-chwang to Pih-li (? = P'ih-chan or Pi-ch'ang between Hami and Turfan), a frontier town of the Kao-ch'ang State. From Pih-li he advanced to Kiao-ho, the Kao-ch'ang capital, now represented by Yar-khoto, a few miles (20 *li*) to the west of Turfan.²