Basically, all the emperors throughout the history of China would marry uncountable wives throughout his life. Except one of them can be crowned as the Empress, the rest of them were normally named as imperial concubines. Anyway, concubine grading system would be different for each dynasty throughout the history of China. There was a common description regarding the concubines of ancient Emperor which sound this way, “Three Palace, Six Courtyard and 72 Concubines”.
Generally, the grading system was almost ranked in such hierarchy by the numbers of concubines might be a little bit different anyway. In Han Dynasty, the Three Palace referred to the Emperor, Empress Dowager and Empress; however in Tang Dynasty, Three Palace signified two Empress Dowager and an Empress.
On other hand, the Six Courtyard which referred to the residences of imperial concubines on the first place were signified the Imperial Concubines after Tang Dynasty. The 72 Concubines did not mean the amount of general concubines but to describe the huge amount of concubines in the palace. In fact, concubine is just a general title for them as there were many grading level for the concubines and the name might be changed in different dynasties. As a whole, all the concubines were the wives of the emperor and they need to serve or ready to serve the emperor for their whole life.
