The south and north developed into a relatively stable equilibrium, due to geographical differences. The flat steppes of the north gave a significant edge to cavalry, while the hilly and mountainous riverlands of the south gave a significant edge to naval warfare. A strong navy on the Yangtze River could protect the south from the north, since cavalry was almost useless in the mountainous riverlands. Likewise, logistical difficulties for the horse-poor south made it difficult to maintain a successful northern campaign. Depending on the relative strengths of the states, the Huai River area and the Sichuan basin were the primary areas of significant territorial changes. This barrier was only overcome by the first of the Sui Dynasty, who built a large invading navy in the Sichuan basin, hence his ability to more easily conquer the south and reunify China.
Despite the political disunity of the times, there were notable technological advances in China. With the invention of the stirrup during the earlier Western Jin Dynasty, not only were cavalry tactics improved immensely, but heavily armored Chinese cavalry also became the norm in this age. Advances in medicine, astronomy, mathematics, and cartography are also noted by historians. The famous Chinese mathematician and astronomer Zu Chongzhi belonged to this age, an intellectual and social product of the elite culture shaped and developed in southern China during this period of time.
The Chinese arts of poetry, calligraphy, painting, and music flourished during this period like never before, as Chinese aristocrats mainly in the south were socially expected to master these as their pastimes. Although the north had its cultural achievements, the south was the place for higher cultural achievement, elitist culture, artistic refinement, and new standards of art that ranked artists according to their various abilities.
The Southern Dynasties
Although powerful in the conquest of the Wu Kingdom in 280 AD, the was severely weakened after the War of the Eight Princes from 291 to 306 AD. During Emperor Huai of Jin and Emperor Min of Jin, the country was put into grave danger with the invasion of the Xianbei tribe from the north. The sieges and ultimate sacking of Luoyang in the year 311 and Chang'an in the year 316 by invading Xianbei armies almost destroyed the dynasty. However, a scion of the royal house, Prince of Longya, fled south to salvage what was left in order to sustain the empire. Cementing their power in the south, the Jin established modern-day Nanjing as their new capital, renaming the dynasty as the Eastern Jin since the new capital was located southeast of older Luoyang.
It was during the Southern and Northern Dynasties period that southern China was greatly developed from its previous state of early Chinese colonization and settlement. Beforehand, the south was inhabited by small and isolated communities of Chinese in a vast uncolonized wilderness of non-Chinese tribes, starting as a near peripheral frontier and changing into a thriving, urbanized, sinicized region of China. In his book ''Buddhism in Chinese History'', Arthur F. Wright points out this fact by stating:
When we speak of the area of the Yangtze valley and below in the period of disunion, we must banish from our minds the picture of the densely populated, intensively cultivated South China of recent centuries. When the aristocrats of the remnants of the Chin ruling house fled to the Nanking area early in the fourth century, the south contained perhaps a tenth of the population of China. There were centers of Chinese culture and administration, but around most of these lay vast uncolonized areas into which Chinese settlers were slow to move.
Although the Chinese of the Eastern Jin were well-defended from the north by placement of naval fleets along the Yangtze River, there were still various problems faced with building and maintaining military strength. The designation of specific households for military service eventually led to a falling out in their social status, causing widespread desertion of troops on many occasions. Faced with shortage of troop numbers, Jin generals were often sent on campaigns to capture non-Chinese tribesman in the south in order to draft them into the military. The Eastern Jin Dynasty fell not because of external invasion, though, but because the regent Liu Yu seized the throne from Emperor Gong of Jin, becoming Emperor Wu of Liu Song .
The southern dynasties of China were rich in cultural achievement, with flourishing of Buddhism and Daoism, especially with the latter as two new canons of scriptual writings were created for the and its rival the . With Buddhism, the southern Chinese were influenced greatly by the writings of monks such as Huiyuan, who applied familiar Daoist terms in describing Buddhism to other Chinese. The Chinese were in contact and influenced by cultures of India and trading partners farther south, such as the kingdoms of Funan and Champa . The Chinese arts of poetry, calligraphy, painting, and playing of music found greater precedent during this age, as their sophistication and complexity reached new heights. The earlier Cao Zhi, son of Cao Cao, is regarded as one of the greatest poets of his day. His style and deep emotional expression in writing gave influence to later poets of this new age such as Tao Qian , or Tao Yuanming. Even during his lifetime, the written calligraphy of the "Sage of Calligraphy", Wang Xizhi , was prized by many and considered a true form of personal expression like other arts. In regards to painting, this art became highly prized with artists such as Gu Kaizhi , who largely established the tradition of landscape art in classical Chinese painting . Institutions of learning in the south were also renowned, including the Zongmingguan , where the famed Zu Chongzhi had studied. Zu Chongzhi devised the new Daming Calendar in 465 AD, calcuated one year as 365.24281481 days , and calculated the number of overlaps between sun and moon as 27.21223 . Using this number he successfully predicted 4 eclipses during a period of 23 years .
The Jin were supplanted by the Liu Song , the Southern Qi , the Liang Dynasty , and then the Chen Dynasty . The rulers of these shortlived dynasties were military generals who were able to seize power for several decades, but unable to securely pass power of rule onto their heirs to continue their dynasty successfully. Emperor Wu of Liang , however, was the most notable ruler of his age, being a patron of the arts and of Buddhism. An avid poet, Emperor Wu was fond of gathering many literary talents at court, and even held poetry competitions with prizes of gold or silk for those considered the best. The authority of the last official Liang Dynasty ruler, Emperor Jing of Liang, was usurped by one of its own successful military generals, Chen Baxian, crowned as Emperor Wu of Chen in 557 AD. Under the later waning leadership of the Chen Dynasty, the southern Chinese were unable to resist the military power amassed in the north by Yang Jian after he defeated his rival General Weichi Jiong. Once Yang Jian usurped the throne from Emperor Jing of Northern Zhou to crown himself Emperor Wen of Sui, his establishment the Sui Dynasty and the invasion of the south reunified the whole of China.
The Northern Dynasties
In the first half of the Northern Wei Dynasty , the Xianbei steppe tribesmen who dominated northern China kept a policy of strict social distinction between them and their Chinese subjects. Chinese were drafted into the bureaucracy, employed as officials to collect taxes, etc. However, the Chinese were kept out of many higher positions of power. They also represented the minority of the populace where centers of power were located, such as the first Northern Wei capital at Pingcheng in modern-day northern Shanxi province.
Widespread social and cultural transformation in northern China came with Emperor Xiaowen of Northern Wei , whose father was a Xianbei, but whose mother was Chinese. Although of the Tuoba Clan from the Xianbei tribe, Emperor Xiaowen asserted his dual Xianbei-Chinese identity, renaming his own clan after the Chinese ''Yuan'' . In the year 493 Emperor Xiaowen instituted a new sinification program that had the Xianbei elites conform to many Chinese standards. These social reforms included donning Chinese clothing , learning the Chinese language , applied one-character Chinese surnames to Xianbei families, and encouraged the clans of high-ranking Xianbei and Chinese families to intermarry. Emperor Xiaowen also moved the capital city from Pingcheng to one of China's old imperial sites, Luoyang, which had been the capital during the earlier Eastern Han and Western Jin dynasties. The new capital at Luoyang was revived and transformed, with roughly 150,000 Xianbei and other northern warriors moved from north to south to fill new ranks for the capital by the year 495. Within a couple decades, the population rose to about half a million residents, and was famed for being home to over a thousand Buddhist temples. Defectors from the south, such as Wang Su of the prestigious Langye Wang family, were largely accommodated and felt at home with the establishment of their own Wu quarter in Luoyang . They were even served tea at court instead of yogurt drinks commonly found in the north.
In the year 523, Prince Dongyang of the Northern Wei was sent to Dunhuang to serve as its governor for a term of fifteen years. With the religious force of Buddhism gaining mainstream acceptance in Chinese society, Prince Dongyang and local wealthy families set out to establish a monumental project in honor of Buddhism, carving and decorating Cave 285 of the Mogao Caves with beautiful statues and murals. This promotion of the arts would continue on for centuries at Dunhuang, and is now one of China's greatest tourist attractions.
In that same year of 523 a revolt of several military garrisons was caused by a food shortage far north of Luoyang. After this was suppressed, the government had 200,000 surrendered garrison rebels deployed to Hebei, which proved later to be a mistake when a former garrison officer organized another rebellion in the years 526?527. The Wei court was betrayed by one of their own generals, who had the empress dowager and the young emperor thrown into the Yellow River, while establishing his own puppet ruler to maintain authority. As conflict swelled in the north between successive leaders, Gao Huan took control of the east and Luoyang by 534, while his rival Yuwen Tai took control of the west and the traditional Chinese capital of Chang'an by 535. Eventually, Gao Huan's son Gao Yang forced the Eastern Wei emperor to abdicate in favor of his claim to the throne, establishing the Northern Qi Dynasty . Afterwards, Yuwen Tai's son Yuwen Jue seized the throne of power from Emperor Gong of Western Wei, establishing the Northern Zhou Dynasty . The Northern Zhou Dynasty was able to defeat and conquer Northern Qi in 577, reunifying the north. However, this success was shortlived, as the Northern Zhou was overthrown in 581 by Yang Jian, who became Emperor Wen of Sui. With greater military power and morale, along with convincing propaganda that the Chen Dynasty ruler Chen Shubao was a decadent ruler who had lost the Mandate of Heaven, the Sui Dynasty was able to effectively conquer the south. After this conquest, the whole of China entered a new golden age of reunification under the centralization of the shortlived Sui Dynasty and succeeding Tang Dynasty .