Why emperor of china have so many concubine?

1.) Because he could

2.) Often times both peasents and officials in the court would offer their daughters in hopes of reciving favours from the Emporor. 3.) The concubines were ladies who relieved the emperor from the great stress that comes with power, as hard as this could sound to other cultures, it was like that. Once an emperor had more than 40000 concubines all around the country, but the more they had, you could say, the worst the emperor would be, there is an ancient legend between the walls of the forbidden city, which says that the emperor should dedicate his time to state matters and not to enjoy the abuse of his power, so as a reminder, there is a human form on a big chicken on every roof of this palace, so this would not be forgotten by the emperor.