In 221 BC, the Qin state unified China by conquering the other six major states and established the Qin dynasty. However, the dynasty lasted 16 years only because its rule was extremely unpopular due to its oppressive policies. In 209 BC, Chen Sheng and Wu Guang started the Dazexiang Uprising to overthrow the Qin dynasty. Although the uprising was crushed, several other rebellions erupted consecutively all around China over the next three years. Many rebel forces claimed to be restoring the former six states, and numerous pretenders to the thrones of the states emerged, resulting in the formation of many insurgent states. In 206 BCE, the last Qin emperor, Ziying, surrendered to Liu Bang and brought an end to the Qin dynasty.