During the Sui dynasty (581-618), it also became responsible for the city gates, the imperial seals, the wardrobe and the palace administration.
These new external duties were reduced in the Tang dynasty (618-907) to just the city gates, the insignia, and the Institute for the Advancement of Literature.
The position of supervising secretary originated in the Department of State Affairs, from where they were transferred to the Chancellery in the early Tang period.
[2] The Chancellery began to decline in significance during the mid-Tang period as it competed in political power with the Central Secretariat.
[3] The Chancellery continued to exist in name only during the Song dynasty (960–1279), while its functions were carried out by the Central Secretariat and the Department of State Affairs.