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 Zhao's army committed a massacre of the city's inhabitants, killing the Jin crown prince, a host of ministers, and over 30,000[1] 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.

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.[2]
References
- "Volume 102: 劉聰載記". Book of Jin. 648. p. 2659.
曜於是害諸王公及百官已下三萬餘人
- Zhenhe, Zhou; Lo, Kathy (1991). "Migrations in Chinese History and their Legacy on Chinese Dialects". Journal of Chinese Linguistics Monograph Series (3): 29–49. JSTOR 23827034.