How was the Tang dynasty made?
The Li family belonged to the northwest military aristocracy prevalent during the reign of the Sui emperors. The mothers of both Emperor Yang of Sui (r. 604-617) and the founding emperor of Tang were sisters, making these two emperors of different dynasties first cousins. Li Yuan (later to become Emperor Gaozu of Tang, r. 618-626) was the Duke of Tang and former governor of Taiyuan when other government officials were fighting off bandit leaders in the collapse of the Sui Empire, caused in part by a failed Korean campaign. In 617, Li Yuan occupied Chang’an and acted as regent over a puppet child emperor of the Sui, relegating Emperor Yang to the position of Taishang Huang, or retired emperor/father of the present emperor. With the news of Emperor Yang’s murder by his general Yuwen Huaji (d.