The Sui dynasty (sui2, ) was a short-lived imperial dynasty of China that lasted from 581 to 618. The Sui unified the Northern and Southern dynasties, thus ending the long period of division following the fall of the Western Jin dynasty, and laying the foundations for the much longer lasting Tang dynasty.
The dynasty was founded by Yang Jian (Emperor Wen of Sui), a member of the ethnically mixed northwestern Chinese military aristocracy which had developed during the previous period of division. The Sui dynasty capital was Chang'an (which was renamed Daxing, modern Xi'an, Shaanxi) from 581 to 605 and later Luoyang (605–18). Emperors Wen and his successor Yang undertook various centralized reforms, most notably the equal-field system, intended to reduce economic inequality and improve agricultural productivity; the institution of the Five Departments and Six Boards (五省六曹 or 五省六部) system, which is a predecessor of Three Departments and Six Ministries system; and the standardization and re-unification of the coinage. They also spread and encouraged Buddhism throughout the empire. By the middle of the dynasty, the newly unified empire entered a golden age of prosperity with vast agricultural surplus that supported rapid population growth.
A lasting legacy of the Sui dynasty was the Grand Canal. With the eastern capital Luoyang at the center of the network, it linked the west-lying capital Chang'an to the economic and agricultural centers of the east towards Jiangdu (now Yangzhou, Jiangsu) and Yuhang (now Hangzhou, Zhejiang), and to the northern border near modern Beijing. While the pressing initial motives were for shipment of grains to the capital, transporting troops, and military logistics, the reliable inland shipment links would facilitate domestic trade, flow of people and cultural exchange for centuries. Along with the extension of the Great Wall, and the construction of the eastern capital city of Luoyang, these mega projects, led by an efficient centralized bureaucracy, would amass millions of conscripted workers from the large population base, at heavy cost of human lives.