Liu Yu 劉裕 (posthumous title Emperor Wu of the Song 宋武帝, r. 420-422), the founder of the Liu-Song dynasty 劉宋, had achieved greatest merits as a military commander over the elite army of the northern quarter
北府兵) during his long-lasting fights against the non-Chinese states in the north, particularly the Later Qin
後秦 (384-417) and the Southern Yan
南燕 (398-410) empires. At the court of the Eastern Jin empire
東晉 (317-420) in Jiankang 建康 (modern Nanjing 南京, Jiangsu) he was able to overcame the powerful regents
Huan Xuan 桓玄 and Lu Xun 盧循 and finally dethroned Emperor Gong
晉恭帝 (r. 418-420) and founded his own dynasty in 420.
One of the first measures he implemented was to put the most important troops directly under imperial command (taijun
臺軍) in order to deprive the eminent families
門閥士族, gaomen shizu
高門士族, or guizu haoqiang
貴族豪強) of their base of power. Furthermore, the important posts of the regional inspectors (cishi
刺史) were to be assigned only to members of the imperial family (zongshi
皇族), and the most important offices of the central government were almost not accessible to members of the gentry
, but only to people of lower social classes (hanmen
寒人), at least in theory. To control and to observe the imperial princes in their princedoms (wangguo
王國) who concurrently served as regional inspectors Liu Yu installed so-called document clerks (dianqian
典簽, 典籤 or zhushuai
主帥) that regularly submitted critical reports of the former's work. Though these document clarks were only officials of a low rank they had a great influence about the political rise and fall of princes because they had a clear insight into their activities. While on the one hand they were able to report plans of rebellions before these could be carried out, they had on the other hand also the power to slander persons they disliked. This kind of harassment often led to political resistance among the Song princes, or to emigration to the Northern Wei empire
北魏 (386-534) in northern China.
After Liu Yu's untimely death his son Liu Yifu 劉義符 became an Infant Emperor 少帝 (r. 422-423) but was soon replaced by his brother Liu Yilong 劉義隆 (posthumous title Emperor Wen 宋文帝, r. 424-453). Emperor Wen was assisted in government by Fu Liang 傅亮 and Xu Xianzhi 徐羡之. Under their administration, a land reform was executed that clearly defined how the gentry was allowed to acquire new land. At the same time, the immigrants from the north that had come to the lower Yangtze region with the foundation of the Eastern Jin dynasty were now fully incorporated into the normal household register system. After the assassination of Xu Xianzhi, Liu Yilong again allowed members of the gentry to occupy government posts. The ensuing court intrigues that involved some of the emperor's brothers and his crown prince, did fortunatley not have a real effect upon the general development of economy. Historians therefore speak of the peaceful and booming years of the Yuanjia reign 元嘉 (424-454).
In 454 Prince Liu Shao 劉劭 murdered his imperial father and ascended to the throne, but in the same year, he was toppled by his brother Liu Jun 劉駿 (posthumous title Emperor Xiaowu 宋孝武帝, r. 453-464) who was able to defeat the rebellion of his uncle Prince Liu Yixuan 劉義宣. Liu Jun again engaged people of a lower social background (suzu
素族) among his advisors, rather than members of the gentry, as his father had done. Emperor Xiaowu's son Liu Ziye 劉子業, the so-called First Deposed Emperor 宋前廢帝 (r. 464-465) tried to extirpate potential rivals within his own family but was soon murdered himself by Liu Yu 劉彧 (posthumous title Emperor Ming 宋明帝, r. 465-472), who, on his own part, used the same bloody method to eliminate other claimants to the throne.
While the Song court was engaged in fratricidal strives the Northern Wei empired managed to conquer vast tracts of land in the River Huai region, but their attempts to to occupy the whole south of China failed.
When Liu Yu died he left the throne to an under-age heir apparent, Liu Yu 劉昱, who was not able to keep the throne for more than four years and was therefore called the Second Deposed Emperor 宋後廢帝 (r. 472-476). The commander of the Right Guard (youwei jiangjun
右衛將軍), Xiao Daocheng 蕭道成, enthroned Liu Zhun 劉準 (posthumous title Emperor Shun 宋順帝, r. 477-479) and acted as the regent of the Song empire. In 479 he dethroned Liu Zhun and ascended the throne himself, thereby founding the Qi Dynasty 齊.
Xiao Daocheng 蕭道成 (posthumous title Emperor Gao of the Qi 齊高帝, r. 479-482) had been called a "saviour of the house of Liu-Song" from its self-lacerating actions and was therefore bestowed with offices, honors and nobility titles (king of Qi 齊王). Yet in 479 he founded his own dynasty that was called Qi. Historians call this his realm also Southern Qi 南齊 or Xiao-Qi 蕭齊 to distinguish it from the somewhat later Northern Qi
北齊 (550-577), a successor state of the Northern Wei. Xiao Daocheng died already in 482 and was succeeded by his son Xiao Ze 蕭賾 (posthumous title Emperor Wu 齊武帝, r. 482-493). Xiao Ze made intensive use of document clerks as a central government instance controlling the activites of the imperial princes and the local governors. He so inherited the political system of the Song dynasty. Similarly, the custom of bloody fights among the imperial princes that had plagued the house of Song, was also adhered to by the house of Qi.
A great problem of each government in the history of China was the fact that free, but poor peasants had the only chance to make a living by transferring their land to influential landowners and so became tenant farmers
on their own former land. They weere not obliged to pay taxes or to deliver duties and corvée labour to the state, but became servants, and often enough serfs, of the landowners. A special problem of the Eastern Jin and the Southern Dynasties was that a great part of the old southern gentry was tax-exempted, a present by which a government of northern immigrants (and the dynastic houses were such) could be politically tolerated by the native gentry in the south. To escape tax obligations, many northern immigrants had falsely registered themselves as being of southern origin. Xiao Ze therefore carried out a broad review of the household registers with the hope to unveil more households that were actually liable to pay taxes and to deliver labour to the government. During this tax review campaign "northernes" unmasked were downgraded as tax-liable households (queji
卻籍 "skipping them from households [with preferential treatment]"). A lot of them therefore rose in rebellion. The most important of these was the uprising of Tang Yuzhi 唐寓之 in the region of modern Suzhou 蘇州, Jiangsu, who even adopted the title of emperor of Wu 吳.
The last decade of the Southern Qi period is characterized by succession struggles. Xiao Ze's sons Xiao Zhaoye 蕭昭業 and Xiao Zhaowen 蕭昭文 were deposed by their uncle Xiao Luan 蕭鸞
(posthumous title Emperor Ming 齊明帝, r. 494-498). Xiao Luan's own sons Xiao Baojuan 蕭寶卷 (Duke of Donghun 東昏侯) and Xiao Baorong 蕭寶融 on their parts fell victim to their distant relative Xiao Yan 蕭衍, the Prince of Liang 梁王, in 502. He founded a new dynasty.
As regional inspector (cishi
刺史) of Yongzhou 雍州 at the border to the Northern Wei empire, Xiao Yan 蕭衍 (posthumous title Emperor Wu of the Liang 梁武帝, r. 502-549) was an experienced military leader. Nonetheless, after founding his own dynasty, he switched over to a mild civilian government and spared the old princes of the Song and Qi dynasties. He neither provoked his own princes and local governors by appointing the infamous spies of the document clerks of the central government, nor tried he to prevent the ambitions of the local gentry from obtaining high governmental posts. He replaced the nine-rank system
九品) for state officials from the Wei period
魏 (220-265) by sixteen classes (shiliuban
十六班) that could only be entered after graduating from the National University
太學) where the Confucian Classics
constituted the curriculum. Emperor Wu himself was an erudite scholar, he composed poems, wrote essays and patronized writers, poets, and artists. During his long rule, important anthologies (Wenxuan
文選, Yutai xinyong
玉臺新詠) and literary critiques (Shipin
詩品, Wenxin diaolong
文心雕龍) were compiled. He also promoted the spread of Buddhism
among the southern aristocracy.
During Emperor Wu's reign the Northern Wei empire disintegrated, and a lot of refugees from the Northern Wei court sought refuge in the south, looking for political support, like Yuan Hao 元顥. A refugee from the Eastern Wei empire
東魏 (534-550), Hou Jing 侯景, supported Emperor Wu in his ambitions to reconquer northern China. Hou Jing later conspired with Xiao Zhengde 蕭正德 to overthrow Emperor Wu and assembled a large army of rebels. The rebels captured the capital Jiankang, and during siege Emperor Wu starved to death. Hou Jing penetrated into the palace and made Xiao Zhengde emperor, then Xiao Wang 蕭網 (posthumous title Emperor Jianwen 梁簡文帝, r. 549-550), afterwards Xiao Dong 蕭棟 (the Prince of Yuzhang 豫章王, r. 551), and finally made himself emperor of a Han dynasty 漢. Since the beginning of the Eastern Jin period, this was the first time that the lower Yangtze area was seriously devastated by military actitivies.
The power struggles after Hou Jing's death in 552, carried out by the princes Xiao Lun 蕭綸, Xiao Yi 蕭繹 (posthumous title Emperor Yuan 梁元帝, r. 552-554), Xiao Ji 蕭紀 (the Prince of Wuling 武陵王, r. 552), Xiao Yuanming 蕭淵明 (the Marquis of Zhenyang 貞陽侯, r. 555), and Xiao Cha 蕭詧, were finally ended by Chen Baxian 陳霸先 who made Xiao Fangzhi 蕭方智 (posthumous title Emperor Jing 梁敬帝, r. 555-557) emperor. In 557, Chen Baxian deposed Xiao Fangzhi and founded his own dynasty named Chen 陳.
Chen Baxian 陳霸先 (posthumous title Emperor Wu of the Chen 陳武帝, r. 557-559) inherited the imperial throne as King of Chen 陳 because he forced the last Liang emperor to hand over to him the "Heavenly Mandate
". After the collapse of the Northern Wei empire, there was a new time of political unrest and military activity in the north and along the borders with southern China. During the disturbances of the last decade of the Liang period, the empire of the Northern Zhou
北周 (557-581) was able to conquer the whole western part of southern China, that is modern Sichuan and Yunnan. Chen Baxian's empire was therefore only half the size of the Liang dynasty's. Furthermore, Chen Baxian was never able to fully control all territories of his empire as well as the political and military activities of the local gentry. It took him a long time to subdue all claimants to the throne from the Xiao family that had survived the foundation of the Chen dynasty. Several Liang princes continued the rule of the Liang dynasty in the so-called Later Liang empire 後梁 (555-587) in the middle Yangtze valley.
The most powerful person in the Chen empire after Chen Baxian's death was Hou Andu 侯安都 who replaced the new emperor Chen Chang 陳昌 immediately with Chen Qian 陳蒨 (posthumous title Emperor Wen 陳文帝, r. 559-566). Chen Qian's son Chen Bozong 陳伯宗, called the Deposed Emperor 陳廢帝 (r. 566-568) was toppled by his own uncle Chen Xu 陳頊 (posthumous title Emperor Xuan 陳宣帝, r. 569-582). Chen Xu's reign was a relatively calm and peaceful period, except the few successless military campaigns of Wu Mingche 吳明徹 against the north.
Meanwhile, at the northern frontier a serious change had taken place. The Northern Zhou empire had conquered its neighbouring state, the Northern Qi
北齊 (550-577) and so controlled the whole north and west of China. The Northern Zhou dynasty itself was destroyed by general Yang Jian 楊堅 who founded the Sui Dynasty
隋 (581-618). For Yang Jian, it was an easy game to conquer the small state of Chen in the south and to reunite China under his rule.