The poem concerns Yang Guifei (719–756), one of the Four Beauties of China. She was married to one of many sons sired by Emperor Xuanzong (685–762) – the eighteenth son, to be exact – when the emperor’s aide noticed her extraordinary beauty and decided to add her to the harem, which was reputed to consist of 3,000 women. (That is an example of classic Chinese hyperbole.) Still, to avoid the appearance of the emperor robbing his son of his wife, she was temporarily made a Buddhist trainee before joining the emperor’s harem. Taizhen, ‘large truth’, is the name given her during that period. She quickly became the Emperor’s favourite, gaining the rank of guifei, ‘noble empress’. (Her personal name was Yuhuan, ‘jewel ring’.) Indeed, Xuanzong loved and indulged her so he utterly neglected governance, causing one of his ranking vassals to revolt. In the ensuing turmoil, he had to hang her, surrendering to his angry soldiers’ demand. ‘In Song of Everlasting Regret’, the famous poem that Po Chui (Bai Juyi; 772–846) wrote to immortalise the affair, her attractiveness is described thus: “She would turn her eyes and smile, she’d become so sensuous in a hundred ways / all the powdered beauties in the six palaces would turn pale.”