Dou Jiande killed him in the name of Sui and made the new-born Yang Zhengdao Duke of Xun.
[2] The Turks realized the usefulness of a puppet government which could rally Sui loyalists to their side;[4] so in 620, Shibi's successor Chuluo Khagan established Yang Zhengdao as the King of Sui,[5] including a "Branch Department of State Affairs", in Dingxiang Commandery.
[2] During the Tang campaign against the Eastern Turks of 629–630, Yang Zhengdao still held court in Dingxiang as a puppet of Illig Khagan.
Illig fled with his army, while a Sogdian advisor surrendered to the Tang with Yang Zhengdao and his grandmother Lady Xiao.
[7][2] In the Zhenguan period (627–649), Yang Zhengdao worked as the Chief Steward of Clothing Service[1][8] (尚衣奉御).