The Peoples Republic of China’s Xinjiang-Uygur Autonomous Region, or eastern Central Asia, is an area that has recently seen large scale ethnic unrest, as the native Uygurs have protested violently against Chinese domination in the region. This thesis is a discussion of the background for why Xinjiang today is under Chinese rule. To and a half centuries ago, in 1755-59, the Manchu Qing dynasty (1636-1911) conquered Xinjiang and incorporated it into their state, and this conquest contributed significantly to Xinjiang’s present status as Chinese-ruled territory. In this thesis I discuss what motives might have driven this Central Asian expansion by the Qing. By employing a theoretical framework that focuses on five types of motives for state expansion, namely resources, commerce, overpopulation, security, and ideology, I examine the Qing annexation of Xinjiang comparatively with the Russian Empire’s policies toward western Central Asia (the Central Asian segment that the Russians ended up expanding into, and which today is known as Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan), and conclude that the Qing expansion was primarily the result of ideological motives. The reason was that the state which ruled Xinjiang at the time, the Junghar Khanate, had close relations with the Tibetan Buddhist establishment, which was an establishment that the Manchus depended on in order to keep their state intact. The Qing was therefore determined to conquer Xinjiang and eradicate its ideological adversary.