Transition from Sui to Tang
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.
Source: Wikipedia — Transition from Sui to Tang (CC BY-SA 4.0)