Emperor Taizong of Tang sends envoys to the Xueyantuo bearing gold and silk in order to seek the release of Chinese prisoners captured during the transition from Sui to Tang.

Emperor Taizong of Tang, previously Prince of Qin, personal name Li Shimin, was the second emperor of the Tang dynasty of China, ruling from 626 to 649. He is traditionally regarded as a co-founder of the dynasty for his role in encouraging his father Li Yuan to rebel against the Sui dynasty at Jinyang in 617. Taizong subsequently played a pivotal role in defeating several of the dynasty's most dangerous opponents and solidifying its rule over China proper.

The Xueyantuo or Sir Tardush were an ancient Tiele tribe and khaganate in Northeast Asia who were at one point vassals of the Göktürks, later aligning with the Tang dynasty against the Eastern Göktürks.

The transition from Sui to Tang (613–628), or simply the Sui-Tang transition, was the period of Chinese history between the end of the Sui dynasty and the start of the Tang dynasty. The Sui dynasty's territories were carved into a handful of short-lived states by its officials, generals, and agrarian rebel leaders. A process of elimination and annexation followed that ultimately culminated in the consolidation of the Tang dynasty by the former Sui general Li Yuan. Near the end of the Sui, Li Yuan installed the puppet child emperor Yang You. Li later executed Yang and proclaimed himself emperor of the new Tang dynasty.