We have published a series of articles on the website weiy.cc that discuss the historical context in which Emperor Gaozu of Tang, Li Yuan, decided to raise an army and establish the Tang Dynasty, which lasted for over three hundred years in ancient China. You can read them if you are interested in the history.
Li Mi Assembles Wagang Village Forces to Capture the Eastern Capital
Starting from the thirteenth year of the Daye era, Li Mi began to reach the peak of his life, and Wagang Village became famous throughout the land, entering a period of rapid development and prosperity. That spring, rebel armies from the south of Zhao and Wei (approximately present-day Henan Province)
Wife of Tang Gaozu Li Yuan, Lady Dou, of Xianbei descent
Perhaps because she was born into a noble Xianbei family and had been influenced by the court environment, Lady Dou was exceptionally intelligent from a young age and possessed a very keen political mind. Regarding the issue with the Turkic empress, the young Lady Dou deliberately found a private moment to solemnly express her political insights to her emperor uncle.
Emperor Gaozu of Tang, Li Yuan, decides to rise in rebellion against the Sui
He seemed to see destiny beckoning him from afar. Li Yuan, full of emotion, said to his second son, Li Shimin, “Tang is our rightful country, and Taiyuan is its place. Now that we have gained this place, it is undoubtedly heaven’s favor and gift. If we do not take it, disaster will surely follow!”