 His Chinese wife, the princess Yicheng, secretly sent a warning of the Turkish plans to Emperor Yang, who took refuge at the commandery seat in present-day Daixian, Shanxi.The Turks began their siege of the town on September 11.Yuwen suggested Emperor Yang select a few thousand elite cavalry soldiers to attempt a break out, but Su Wei and Fan Zigai (樊子蓋) persuaded Emperor Yang not to attempt this.