Disaster of Yongjia

The Disaster of Yongjia (simplified Chinese: 永嘉之乱; traditional Chinese: 永嘉之亂) refers to an event in Chinese history that occurred in 311 CE (5th year of the Yongjia era of the reign of Emperor Huai of Jin, hence the name), when forces of the Xiongnu-led Han-Zhao dynasty captured and sacked Luoyang, the capital of the Western Jin dynasty. After this victory, Han's army committed a massacre of the city's inhabitants, killing the Jin crown prince, a host of ministers, and over 30,000 civilians. They also burnt down the palaces and dug up the Jin dynasty's mausoleums. This was a pivotal event during the Upheaval of the Five Barbarians and the early Sixteen Kingdoms era, and it played a major role in the fall of the Western Jin dynasty in 316 CE.

Aurel Stein discovered 5 letters written in Sogdian known as the "Ancient Letters" in an abandoned watchtower near Dunhuang in 1907. One letter in the collection was written by the Sogdian Nanai-vandak addressed to Sogdians back home in Samarkand, informing them about a mass rebellion by Xiongnu Hun rebels against their Han Chinese rulers of the Western Jin dynasty. He further informed his people that every single one of the diaspora Sogdians and Indians in the Chinese Western Jin capital Luoyang died of starvation due to the uprising. The Han Chinese emperor abandoned Luoyang when it came under siege by the Xiongnu rebels and his palace was burned down. Nanai-vandak also said the city of Ye was no more as the Xiongnu rebellion resulted in disaster for the Sogdian diaspora in China.

The Disaster of Yongjia was a major impetus for the mass migration and expansion of Han people into southern China. Many clan genealogies ascribe this event in particular as the reason why their ancestors moved from the north to places in Fujian, Guangdong, etc.