Uyghurs
Rian Thum explored the concepts of identity among the ancestors of the modern Uyghurs in Altishahr (the native Uyghur name for eastern Turkestan or southern Xinjiang) before the adoption of the name "Uyghur" in the 1930s, referring to them by the name "Altishahri" in his article "Modular History: Identity Maintenance before Uyghur Nationalism". Thum indicated that Altishahri Turkis did have a sense that they were a distinctive group separate from the Turkic Andijanis to their west, the nomadic Turkic Kirghiz, the nomadic Mongol Qalmaq, and the Han Chinese Khitay before they became known as Uyghurs. There was no single name used by them to refer to themselves, the various native names Altishahris used to refer to themselves were Altishahrlik (Altishahr person), yerlik (local), Turki, and Musulmān (Muslim), the term Musulmān in this situation did not signify religious connotations, because the Altishahris would exclude other Muslim peoples like the Kirghiz when referring to themselves as Musulmān. Dr. Laura J Newby has also noted that the sedentary Altishahri Turkic people felt themselves as a separate group from other Turkic Muslims since at least the 19th century.
Uyghurs
The ancient Uyghurs believed in Shamanism and Tengrism, then Manichaeism, Buddhism and Church of the East. People in the western Tarim Basin region began to convert to Islam in significant number early in the Kara-Khanid Khanate period. There had been Christian conversions in the late 19th and early 20th centuries but these were suppressed by the First East Turkestan Republic government. Modern Uyghurs are now primarily Muslim, and they are the second largest predominantly Muslim ethnicity in China after the Hui.