Catastrophe of Yanchang

The Catastrophe of Yanchang (延昌之祸) refers to the fall of Luoyang, the capital of the Zheng Empire at that point, to nomadic invaders from the north who would eventually found the Zhao, Former Yan and Former Yong regimes.

Aftermath
The young emperor, newly captured, was imprisoned in Luoyang, while the erstwhile Prince of Yingchuan (who would later become Emperor Jing of Zheng) officially took up the Imperial mantle, surrounded by the refugee officials, in Jiankang.

The situation north did not remain stable for long. Amid the slaughter and flight in the north, the Zhao regime quickly launched an invasion of Zheng on the pretext of returning the body of the young Emperor, sparking off the First Zheng-Zhao War.