Greatness, Fall, and Rebirth: At the beginning of the fifth century, China is in disarray. The Xiongnu warlord Juqu Mengxun breaks through the fortress walls and captures Dunhuang. Together with the Indian Buddhist monk Dharmaksema, he begins to build magnificent cave temples at Mogao. In 655, Wu Zetian becomes empress of the Tang Empire. Women gain greater freedom and Buddhism spreads to Japan and Korea. But despite progress, decline threatens.