Chinggis's campaign into the Muslim world of Central Asia, a watershed in the region's history, completed his transformation from a successful nomadic chieftain on the fringes of China to a world-conqueror on an unparalleled scale. The speedy annihilation of the Qara Khitai and Khwārazm (Khorezm) Shāh realms not only drastically enlarged the territories and manpower under Chinggis's control, but also bolstered his public image as someone predestined by Heaven to conquer the entire world. Moreover, these conquests closely exposed him to Muslim sedentary culture, different from that of China, which for centuries had been the major reference point for the nomads of Mongolia, thereby greatly enlarging the stock of administrative, military and cultural tools at his disposal. As for Central Asia, much of the region's subsequent political culture, ethnic composition and concepts of legitimacy and law go back to Chinggis Khan. Yet the century and a half that followed the Mongol conquest was far from being the region's golden age. Moreover, the history of Chinggisid Central Asia, largely associated with the Chaghadaid khanate, is less studied in comparison with contemporary Mongol states or with other periods of Central Asian history, because of the paucity of written sources. This chapter reviews the political history of Central Asia under the Mongols up to 1347 and then briefly discusses major economic and cultural-religious phenomena.