Xuanzong (reigned 712-756) was the Tang dynasty's longest-ruling emperor. His reign was mostly glorious politically, economically, and culturally, but ended catastrophically with the An Lushan Rebellion, among the most destructive events in Chinese history. He is most famous for his love for concubine Yang Guifei, which ended tragically when soldiers forced him to have her killed during the rebellion. Xuanzong's reign, and especially the An Lushan Rebellion that ended it, saw the early stages of developments that were to form a transition to a new and different period in Chinese history.