Yang Dong (; 600s–619), known in traditional histories by his princely title of Prince of Yue (越王) or by his era name as Lord Huangtai (皇泰主), posthumous name (as bestowed by Wang Shichong) Emperor Gong (恭皇帝), courtesy name Renjin (仁謹), was an emperor of the Chinese Sui dynasty. During the disturbances that permeated throughout the Sui state late in the dynasty's history, his grandfather Emperor Yang left him in charge of the eastern capital Luoyang, and after Emperor Yang was killed by the general Yuwen Huaji in 618, the Sui officials in Luoyang declared Yang Dong emperor. However, soon one of those officials, Wang Shichong, seized power, and in 619 had Yang Dong yield the throne to him, ending Sui. Soon, he was killed on Wang's orders. During Emperor Yang's reign It was not recorded when Yang Dong was born, except that his elder brother Yang Tan (楊倓) was born in 603 and his younger brother Yang You was born in 605. He was the second of three sons of Yang Zhao, Emperor Yang's son and crown prince. His mother was Yang Zhao's concubine, Consort Liu. In 606, Yang Zhao died. According to Confucian principles of succession, Yang Dong's younger brother Yang You, would have been considered Yang Zhao's heir and successor, as Yang You was born of Yang Zhao's wife Crown Princess Wei. However, Emperor Yang did not create any son of Yang Zhao crown prince to replace Yang Zhao, but left the matters of succession ambiguous between them and Yang Zhao's younger brother Yang Jian the Prince of Qi. He did, however, create Yang Dong and his brothers imperial princes, and Yang Dong was created the Prince of Yue. In spring 613, when Emperor Yang launched his second of three campaigns against Goguryeo, he left the eight-year-old Yang Dong nominally in charge of the eastern capital Luoyang, with the official Fan Zigai () actually responsible. Subsequently, while Emperor Yang was in Goguryeo territory, the general Yang Xuangan rebelled near Luoyang, and Fan defended Luoyang under Yang Dong's command. The general Wei Wensheng (), leading the army from the capital Chang'an under Yang You's command, came to Luoyang's aid, and Emperor Yang also abandoned the Goguryeo campaign and sent the generals Yuwen Shu and Lai Hu'er () back to the Luoyang region; these Sui generals together defeated Yang Xuangan. In 616, with most of Sui territory, particularly the northern