They are the most famous maids of the Prince of Jing'an. A Chang'an song goes:
Jinghong Fairy,
Dance gracefully,
Pingting smiled,
Mo Yan Jiang Shan.
Yes, they are the maids of Prince Jing'an of the Kingdom of Jin: Wanyan Jinghong, Liu Pianran, Bai Pingting and Guan Moyan.
There is nothing in the world that they cannot handle!