Sui dynasty

The Sui dynasty ruled China for 37 years, from 581 to 618 AD, founded by Yang Jian, who took the name Emperor Wen of Sui after usurping the Northern Zhou throne. Its capital was Daxing, on the site of modern Xi'an, from 581 to 605, and Luoyang thereafter. Covering roughly 3 million square kilometers, the Sui reunified China proper after the long division of the Northern and Southern dynasties period, constructed the Grand Canal linking the empire's eastern and western economic centers, extended the Great Wall, established the equal-field land system, reformed the bureaucracy and promoted Buddhism; its population reached about 46 million by 606 AD. The dynasty collapsed after failed military campaigns against Goguryeo ending in defeat by 614 AD, widespread popular revolts and heavy taxation, and Emperor Yang was assassinated by his minister Yuwen Huaji in 618, after which Li Yuan founded the succeeding Tang dynasty.