In the year 140 BC, Jing-di was succeeded by his son, Liu Zhe (Emperor Wu/Wu-di), a bright and spirited sixteen-year-old. Emperor Wu's reign prolonged the prosperity of the Dynasty. Wu-di's reign began with a hands-off approach to commerce and economy, which allowed more growth in the economy's private sector.
Wu-di kept his civil administrators under a tight rule, and treated the slightest protest as disloyalty. He ended his father's compromise with the nobility, waged war against China's most defiant Princes, and gave more control to his civil servants on a local level.
Emperor Wu changed the laws on inheritance. Instead of a family's land remaining under the eldest son, he gave all sons the right to an equal part of their father's land. This was done to break the larger estates into smaller pieces.
In 138 BC, Wu-di sent China's first known explorer, Zhang Qian to Parthia, west of Bactria, to establish relations with Kushan.
In the twentieth year of Wu-di's rule, Confucianism became China's official political philosophy. Confucianism began to dominate in the civil service, while legalist rivals continued to hold their positions.
Examinations for China's 130,000 civil service positions were based on the applicant's knowledge of Confucianism, knowledge of ancient writings and rules of social grace, rather than technical expertise.
Theoretically, these examinations were open to all citizens, but in reality, they were only for those with adequate respectability. Artisans, merchants and others of a class lower than gentry were excluded. No doubt, some of these people could have served China well.
On the job, training for civil servants occurred in bureaucracies at the local level, and merit became a consideration before and after a civil servant's apprenticeship.
A young man who proved himself as a clerk may become a manager. After proving himself as a manager, he might move up to a position as an advisor in attendance at the Emperor's palace, or move to a high position at a regional capital.
With the economic prosperity during Wu-di's rule, allowed China to wage war. Wu-di believed he was strong enough to oppose the Xiong Nu, and wanted to end the payments to the tribes that were started by Liu Bang. However, Wu-di was concerned that the Xiong Nu might send an army into Northern China's sparsely populated steppe lands, or that they would ally themselves with the Tibetans. After securing his trade routes to Central Asia, Wu-di launched a series of military campaigns. Though his generals led the troops for him, Wu-di gained recognition as a ruler of vigour and bravery.
Wu-di's attack on the Xiong Nu was costly in manpower, but it pushed most of the Xiong Nu back from China's northern frontier.
Almost two million Chinese citizens migrated into the newly acquired territory, and Wu-di established new colonies of soldiers and civilians. The Xiong Nu who stayed behind became farmers, were drafted for construction labour, or employed as farm labourers. Moreover, even some of them were drafted into the Chinese army, their families forced to remain were they were as hostages against treason.
The war against the Xiong Nu stimulated exploration farther westward. After thirteen years of captivity by the Xiong Nu, Zhang Qian went back to Wu-di's court to give him the first reliable description of Central Asia.
Wu-di ordered Zhang Qian and his assistants back to Central Asia, and they gathered information about India and Persia and explored the fertile farmlands of Bactria.
These explorations and China's success against the Xiong Nu brought an exchange of envoys between China and states to the west. Moreover, more importantly for China, this opened up the 4,000-mile trade route that would be known as the Silk Road. China began breeding a superior breed of horses, and it began growing Alfalfa and grapes.
Wu-di learned more about the origins of the products they were importing. For added revenues, Wu-di demanded that the neighbouring states pay his Empire to sell their goods to the Chinese, and he began military campaigns to force them to do so.
In 108 BC, Wu-di sent his forces northeast and conquered an iron-using Kingdom in northern Korea. This Kingdom was similar to the states of China before Liu Bang united them, and it harboured many Chinese refugees from the previous century.
In the south, Wu-di's armies conquered territory lost during the civil war that brought the Han to power, including the port town of Guangzhou. Chinese immigrants followed the army closely and occupied the new territories.
After a long and tiresome struggle, the Chinese army managed to conquer Northern Vietnam, an area that the Chinese called Annam (Tang Dynasty), which means "Pacified South". Chinese immigrants came here as well, and some would settle near the Annamite Mountains in Central Vietnam.
The Chinese introduced Vietnam to the water buffalo, metal plows, and other tools, and they brought them their written language. They divided Annam into administrative areas; each administration was responsible for collecting taxes and drafting soldiers.
However, Chinese rule in Annam would remain tenuous, its jungles and mountains gave sanctuary to Vietnamese who would conduct continuous raids against the Chinese settlements.
Wu-di's war of expansion and maintenance of large armies were a burden on the economy. They offset the benefits of the increase in trade followed by those conquests. Imports contributed more to the pleasures of the wealthy than they did to China's economic vitality. Legalist officials made it worse by being hostile to private tradesmen, and they led a drive for government control of the economy.
Because of this, the government levied new taxes on carts and boats, and took over China's most profitable industries: salt and iron. Moreover, with the rise in government influences the economy suffered.
With the growth of peasant population and the increase of land owned by the wealthy, a shortage of land appeared. Gentry bureaucrats bought more land out of precaution, and often abused their position to do so, and they were able to make their land tax exempt.
Ordinary peasants were paying a larger share in taxes, resulting in the need to loan money. Farming productivity declined. Many peasants were evicted or were forced to leave farming, making more land available to the gentry. Some peasants resorted to banditry, and some struggling peasants sold their children into slavery.
Conscription into the military and conscription for labour added to the peasantry's discontent. China's most renowned Confucian scholar, Dong Zhongshu, was outraged by the plight of the peasants and led the way in expressing concern about social decay. He claimed that the vast extend of lands was owned by the wealthy, while the poor had no spot to plant their feet on. He complained about the extreme taxes and pointed out that poorer farmers could not afford metal working tools to speed up their productivity.
Dong Zhongshu proposed to Wu-di a remedy for the economic crisis: reduce taxes for peasants, reduce amount of unpaid labour that civilians had to do for the local bureaucracy, abolish the government's monopoly on salt and iron, and improve land distribution.
Wu-di wanted to help the peasants but was deceived by gentry administrators. Confucianists led the drive for reform, but gentry Confucians did not want to go against their own economic interests.
Wu-di's only substantial response was to lower taxes for the poor, and levy higher taxes for the wealthy. He also sent out spies to report on possible tax evaders. He chose to ignore land distribution, not wishing to offend wealthy landowners, believing he needed their cooperation to finance his military campaigns.
In 91 BC as Wu-di's fifty-four year reign neared its end, a violent war erupted around the capital about who was to succeed him. On one side was the Empress with her heir apparent and on the other side was one of Wu-di's concubines. The two families came close to destroying each other. Then, just before Wu-di's death, a compromise heir was chosen: the eight-year-old Liu Fuling, who was to be known as Zhao-di, was put under the regency of Huo Guang, a former general.