Believed to be the first dynasty in traditional Chinese history, the Xia (Hsia) dynasty is described in ancient chronicles such as the Bamboo Annals, yet some historians question its existence and consider it to be mostly mythological. The exact dates of this dynasty are unclear, but are generally agreed to be circa 2070 BCE–1600 BCE. Prior to the Xia dynasty, legend recounts that the Three Sovereigns and then the Five Emperors first ruled China. Yu the Great, after building canals to solve the flooding of the Yellow River, then became the king of Xia. After a 45-year rule, his son Qi succeeded him, introducing the concept of hereditary succession in China. The Xia were predominantly farmers and made great advances in their society, for example introducing bronze casting and tools, developing irrigation systems, oven-baking bricks and making silk clothing. Seventeen Xia rulers are recorded; the last, the tyrannical King Jie, was overthrown by Tang, who founded the Shang dynasty.