Moreover, the three thousand makeup in the harem does not refer to all the emperors' concubines, but to all the women in the harem, including maids, maids and mammy. Of course, the emperor can also pamper women except concubines in public, but the sum of words is only a few dozen people at most, which is not as exaggerated as 3 thousand said.
We can also see from Empresses in the Palace that the emperor can marry a concubine at any age, regardless of status, as long as he likes. There are certain conditions for being a maid of honor. For example, in Ruyi's Love in the Palace, the imperial concubine's predecessor was a humble maid-in-waiting, and her father also had an official position, but her father died earlier and there was no one at home. She could only enter the palace under the banner of maid-in-waiting, but fortunately she later became a imperial concubine.
However, it takes some ability to stand out from so many ladies-in-waiting and become the emperor's concubine. First of all, if you are a maid-in-waiting far away from the emperor's residence, you will never have a chance to meet the emperor in your life, let alone be loved by him. Moreover, if you want to be a palace maid, you have to abide by many rules. For example, many emperors asked women in the harem to read "Women's Training" to ensure a good atmosphere in the harem and prevent moral corruption from damaging the royal family's face.