Beijing became the capital of China after the Mongol invasion of the 13th century, completing the easterly migration of the Chinese capital begun since the Jin dynasty. The Ming uprising in 1368 reasserted Chinese authority and fixed Beijing as the seat of imperial power for the next five centuries. The Emperor and the Empress lived in palaces on the central axis of the Forbidden City, the Crown Prince at the eastern side, and the concubines at the back (therefore the numerous imperial concubines were often referred to as "The Back Palace Three Thousand").