Floods submerged more than thirty commanderies in Shandong and Henan, and people sold one another as slaves; the levies for Goguryeo gave rise to bandits. (History of the Northern Dynasties (Beishi), Annals 北史 卷12 大業7年)
An edict declared that Goguryeo under Gao Yuan had abandoned the protocol of a vassal state, and announced plans to campaign against Liaodong. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業7年2月)
Over thirty commanderies of Shandong and Henan were flooded, and the people sold themselves as slaves. (Book of Sui (Suishu), Imperial Annals 隋書 卷003 帝紀 大業7年7月)
In July 611, laborers and boats from south of the Yangtze and Huai carry the grain of the Liyang and Luokou granaries to Zhuojun; the transport stretches a thousand li, with tens of thousands travelling at any time, and corpses litter the roads. (Zizhi Tongjian (Comprehensive Mirror) 권181 611년 항)
In October 611 (Yimao day), the Dizhu pillar collapses and the Yellow River flows backward for tens of li. (Zizhi Tongjian (Comprehensive Mirror) 권181 611년 항)