You should watch the old Netflix series Marco Polo. The scene in Kublai Khan's harem where they do the women selection.
Anyone who failed the test will be sold as a sex slave in a low end brothel, and only those who pass can have the pleasure of pleasuring the great Khan himself.
A bit sad for the Chinese lady, the sister of the Song Dynasty Regent. She was sold into the harem for the sole purpose of assassinating Kublai Khan, and was terminated by Chabi Khatun for being "too good".