1. One of the 3 world beauties and also the byword of the historically most beautiful woman, “Yang Guifei” was an actual figure loved by the Tang Dynasty’s 6th emperor Xuanzong of the 8C. It is reported that Yang Guifei enjoyed consuming bird’s nest.
2. In Bencaogangmu’s addendum, it is introduced as the substance which “makes skin lustrous and provides energy.”