According to "Biography of Yang Guifei in Old Tang Dynasty", after Chen killed Yang and his son, he wanted to kill Yang Guifei again to avoid future troubles. In desperation, Emperor Xuanzong of the Tang Dynasty gave Yang Guifei a white silk, and Yang Guifei hanged herself under a pear tree in a Buddhist temple at the age of 38. This is the allusion in Bai Juyi's Song of Eternal Sorrow. People in the army stopped, and no one moved until they trampled those moths under the horseshoe.
The origin of the name
Yang Yuhuan's name is not recorded in Old Tang Book and New Tang Book, nor is it clearly recorded in Zi Tong Zhi Jian. The legend of Song of Eternal Sorrow only says that she is "Yang Xuanyan's daughter". In the ninth year of the Tang Dynasty (855), that is, about 100 years after the death of Yang Guifei, Zheng Chuhui's Miscellanies of Ming Taizu first mentioned: "Yang Guifei's small character Yuhuan".
Later generations still use it today. Yang Guifei's three names "Jade Slave", "Yu Niang" and "Yuhuan" are real, and the expressions of slave, mother and ring all set off Yang Guifei's names in different periods. Yunu was her childhood nickname; Yu Niang was her honorific title before her canonization; Yuhuan is her nickname after she was made a noble princess and gained weight.
Refer to the above? Baidu Encyclopedia-Yang Yuhuan