The future Princess Pingyang was the third daughter of Li Yuan, then Duke of Tang, a hereditary nobleman of Sui China and cousin of Emperor Yang.

In 617, Li Yuan, then the general in charge at Taiyuan was planning to rebel against Emperor Yang of Sui, by whom he had been imprisoned before.

He sent messengers to his daughter and son-in-law Chai Shao, then at the Sui capital Chang'an, summoning them back to Taiyuan.

Pingyang hid initially, but then distributed her wealth to several hundred men, receiving their loyalty, so she rose in support of Li Yuan.

[2] Late in 617, Li Yuan crossed the Yellow River into the Chang'an region and sent Chai Shao to rendezvous with her.

[4] There is speculation of various other causes including assassination from her brothers and sacrifice during battle, however, these seem improbable, especially considering there were no records of her fighting after Chang’an.