Properly called the On Uyghur Toquz-Oghuz Orkhon Khanate, the Uyghur Khaganate stretched from the <a href="http://en.wikipedia.org/wiki/Caspian_Sea" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Caspian Sea</a> to <a href="http://en.wikipedia.org/wiki/Manchuria" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Manchuria</a> and lasted from AD 745 to 840. It was administered from the imperial capital <a href="http://en.wikipedia.org/wiki/Ordu-Baliq" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Ordu-Baliq</a>, the first city built in Mongolia. During the imperial phase, the term Uyghur (Chinese:维吾尔; pinyin: <em>Wéiwú'ěr</em>) denoted any citizen of the Uyghur Khaganate, as opposed to the Uyghur tribe.

Large numbers of <a title="Sogdiana" href="http://en.wikipedia.org/wiki/Sogdiana" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Sogdian</a> refugees came to Ordu-Baliq to escape the Islamic conquest of their homeland. They converted the Uyghur nobility from Buddhism to <a href="http://en.wikipedia.org/wiki/Manichaeism" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Manichaeism</a>. Thus, the Uyghurs inherited the legacy of Sogdian Culture. Sogdians ran the civil administration of the empire. They were helpful in outflanking the Chinese diplomatic policies which had destabilized the Göktürk Khaganate. In AD 840, following a famine and civil war, the Uyghur Khaganate was overrun by the <a class="mw-redirect" title="Kirghiz" href="http://en.wikipedia.org/wiki/Kirghiz" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Kirghiz</a>, another Turkic people. As a result the majority of tribal groups formerly under Uyghur control migrated to what is now northwestern China, especially to the modern <a href="http://en.wikipedia.org/wiki/Xinjiang" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Xinjiang</a> Uyghur Autonomous region.

Several laws enforcing racial segregation of foreigners from Chinese were passed by the <a href="http://en.wikipedia.org/wiki/Han_Chinese" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">Han Chinese</a>during the Tang dynasty. In 779 the Tang dynasty issued an edict which forced Uyghurs in the capital to wear their ethnic dress, stopped them from marrying Chinese females, and banned them from pretending to be Chinese. Chinese disliked Uyghurs because they practiced <a href="http://en.wikipedia.org/wiki/Usury" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">usury</a> The magistrate who issued the orders may have wanted to protect "purity" in Chinese custom.<sup id="cite_ref-24" class="reference" style="line-height: 1em; font-style: normal; font-weight: normal">
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