Here are some references to the 8th century Uyghur Khaganate or Uyghur Empire:
Sinor, Peter, Editor; The Cambridge History of Early Inner Asia; Cambridge University Press; 1994; Chapter 12 pages 317-342.
Barthold, W.; Turkestan Down to the Mongol Invasion; Munishiram Manoharlil Publishers Pvt Ltd; 1992
Grousset, Rene; The Empire of the Steppes a History of Central Asia; Rutgers University Press; 1997
