Three Departments and Six Ministries system

Timeline

1. 501–580Chang'an · ShaanxiThe Northern Zhou modeled its offices on the Rites of Zhou, gradually forming a division of functions among the Inner Writing (Zhongshu), Chancellery, and Department of State Affairs, providing a direct institutional source for the Sui three-department system.
2. 581–589Daxing City · ShaanxiEmperor Wen of Sui abolished the Northern Zhou official system and established a three-way division of decision-making and administrative power among the Secretariat (Neishi Department), the Chancellery, and the Department of State Affairs; the Department of State Affairs directed the various bureaus, forming a stable framework of central government during the Kaihuang era.
3. 590–600Daxing City · ShaanxiUnder the Sui, the Department of State Affairs had six bureaus—personnel, rites, war, justice, revenue, and works (formally named the six ministries in the Tang)—handling selection, ritual, military affairs, judicial cases, finance, and public works; the basic outline of the Three Departments and Six Ministries system had already taken shape by late Kaihuang.