Political History of the Sui Dynasty

Yang Zhong 楊忠 was a general among the nobility of the empire of Western Wei 西魏 (535-556) and then of its successor state of Northern Zhou 北周 (557-581). He was given the title of Duke of Sui 隋. His son Yang Jian 楊堅 was likewise an eminent general that had his daughter married to Emperor Xuan of the Northern Zhou 北周宣帝 (r. 578-579), whereupon he was appointed Counsellor-in-chief. After the death of Emperor Xuan and the accession of the under-age prince Yuwen Chan 宇文闡 (Emperor Jing 北周靜帝, r. r. 579-581) Yang Jian acted as regent and controlled all imperial armies. To prevent the imperial princes from usurpation he summoned them to the capital and had them executed. Yang Jian was able to suppress the rebellion of three commanders-in-chief (zongguan 總管, the so-called Sanfang 三方), Yuchi Jiong 尉遲迥, Sima Xiaonan 司馬消難, and Wang Qian 王謙. In 581 Yang Jian dethroned Emperor Jing and founded his own dynasty that was called Sui, like his ducal estate.
Yang Jian was the person who finally suceeded in reunifying China after almost four hundred years of divison between north and south. It was not only his own work, but the reunification had already been prepared by the Northern Zhou court where reforms were introduced to enhance the state power over the aristocracy, the military and the Buddhist clergy. It was especially the Confucian system of recruiting state officials among the graduates of state schools by means of examinations was newly considered as very useful. After Yang Jian founded his dynasty, he energetically carried on these reforms. The conquest of southern China was a well-prepared enterprise, and the troops of the young Sui dynasty found almost no resistance by the Chen 陳 (557-589), the last of the Southern Dynasties 南朝 (420~589).
While the south had been politically weak during the last decades of the Southern Dynasties period as a cause of incessant struggles among the imperial families and the local gentry, the population of the Sui empire was already quite homegenous and consisted of a mixture of Chinese and non-Chinese peoples. The long reign of the Northern Wei dynasty 北魏 (386-534) of ethnic Xianbei 鮮卑 origin (Beiwei 北魏) had laid the foundation for the economic and political reconstruction of northern China after half a century of turmoils.
Yang Jian had broken the power of the northern aristocracy and the resistance of ministers that were still loyal to the dynasties of the Northern Qi 北齊 (550-577) and Northern Zhou. The mightiest families of the south were resettled to the region around the capital Chang'an 長安 (modern Xi'an 西安, Shaanxi) and so deprived them of their domains and their economical and social base. An ensuing rebellion of the southern aristocracy was suppressed by general Yang Su 楊素. The next step of the Sui was to reorganize the local administration throughout the empire. The double administration of civilian and military superior prefectures (zhoufu 州府 and junfu 軍府) was given up, the commanderies (jun 郡) were reorganized into prefectures (zhou 州), and the general prefectures (zongguanfu 總管府) were abolished. In the central government, the structure of the three departments (sansheng 三省) and six ministries (liubu 六部) was perpetuated and served as model for the Tang dynasty 唐 (618-907). Princedoms (wangguo 王國) as quasi-independant kingdoms within the empire with a separate own administratorial structure and own military forces were given up and would never play a political role in China. The rank system for officials in the state service still followed the pattern of the nine ranks (jiupin zhongzheng 九品中正) that had been implemented by the Cao-Wei dynasty 曹魏 (220-265). The Sui government created two grades for supplicants of official career: jinshi 進士 ("presented scholar") and mingjing 明經 ("classicist"). Furthermore, military service and military career in the garrison militia (fubing 府兵) that had been restricted to people of Xianbei ethnicity before, was opened to Chinese, and the special military households (binghu 兵戶) were given up. The Sui emperors also newly codified the imperial law, first in the Kaihuang Codex 開皇律, and later in the Daye Codex 大業律. Last but not least, several economical reforms critically contributed to the integration of the various regions of China into the Sui empire, namely the issuing of a common currency, the equal-field-system, and the construction of the imperial canal.
Yang Jian (Emperor Wen 隋文帝, r. 581-604) nominated Yang Guang 楊廣 as his successor (posthumous title Emperor Yang 隋煬帝, r. 604-617). The rebellion of his brother Yang Liang 楊諒 was suppressed by the loyal prince Yang Su. Emperor Yang personally conducted military campaigns against the Türks (Tujue 突厥) and the Tuyuhun 吐谷渾 to secure the northwestern border regions. Several prefectures were established in the Western Territories with the aim to control the access to the Inner Asian trade routes. Diplomatic missions were sent to several states in Central Asia, the Middle East, East and Southeast Asia.
In 610 the first rebellions among the population showed that the Sui empire, being at its political and economical height, on the other had imposed a heavy burden on the peasant population. The buildings in the capitals, especially in Luoyang and in a third capital, Jiangdu 江都 (modern Yangzhou 揚州, Jiangsu), the erection of fortification walls in the north, and of dykes along the Yellow River, and the construction of the Great Canal exhausted the labour power of the population, especially in the lower Yangtze and Yellow River areas. The rebellion of Prince Yang Jian ended in the execution of thousands of alleged collaborators, a harsh punishment that contributed to the decreasign popularity of the Sui regime. The permanent travels of Emperor Yang between the many capitals likewise helped exhausting of the state treasury.
The final spark that enflamed the suppressed population were the three successless campaigns against the Korean kingdom of Koguryŏ 高句麗 since 608. Droughts and unindations further imposed a high toll on the suffering population of the Yellow River Plain. In 611 Wang Pu 王蒲, called "Zhishi Lang 知世朗", and Liu Badao 劉霸道 in the region of modern Shandong were the first to stage an uprising against the exploitation by the Sui government. Another groups of rebels was headed by Sun Anzu 孫安祖 and Dou Jiande 竇建德 in modern Hebei. The largest rebellion movement was that of Wagang 瓦岡, led by Di Rang 翟讓. From the south, rebellious peasant armies were lead by Du Fuwei 杜伏威 and Fu Gongshi 輔公祏. All these rebellions that one by one spread over the whole of China converged to three main movements: the Wagang army led by Di Rang, later by Li Mi 李密 (modern Henan); Du Jiande's army that defended a kingdom called Xia 夏 (modern Hebei); and Du Fuwei's kingdom of Wu 吳 (modern Anhui, northern Jiangsu). Except peasants, there were also rich landowners and members of the old southern aristocracy that had been resettled in the north. Their most important representative was Yang Xuangan 楊玄感, a member of the imperial family, whose rebellion in 613 caused the defeat of the second Korean campaign. Another relative of the imperial house, Li Yuan 李淵, resident regent staying in the capital to take care of things (liushou 留守) of Taiyuan 太原 (modern Taiyuan, Shanxi), staged a rebellion in 616 and occupied the capital Chang'an. He dethroned Emperor Yang and enthroned the Prince of Dai, Yang You 楊侑, as emperor (posthumous title Emperor Gong 隋恭帝, r. 617-618). The extreme ruthlessness of Emperor Yang against opponents and rebels - it is said that in some cases more than 30,000 people were executed - contributed to his defamation as the typical evil last ruler of a dynasty. In 618 Emperor Yang was killed with the help of his minion Yuwen Zhi 宇文智, and the young Prince of Qin 秦, Yang Hao 楊浩, was installed as emperor. In the capital, meanwhile, Yang Tong 楊侗, Prince of Yue 越, was made emperor. Yang Hao was murdered by Yuwen Huaji 宇文化及 who proclaimed himself emperor of Xu 許. In Luoyang, Li Mi and general Wang Shichong 王世充 fought for the imperial house. Li Mi surrendered to Li Yuan, who had just founded his Tang dynasty 唐, and Wang Shichong made himself emperor of Zheng 鄭. The Sui dynasty so had come to an end, and was replaced by Li Yuan's Tang dynasty.