The southward expansion of the Han dynasty was a series of Chinese military campaigns and expeditions in what is now modern Southern China and Northern Vietnam. Military expansion to the south began under the previous Qin dynasty and continued during the Han era. Campaigns were dispatched to conquer the Yue tribes, leading to the annexation of Minyue by the Han in 135 BC and 111 BC, Nanyue in 111 BC, and Dian in 109 BC.
Han Chinese culture took root into the newly conquered territories and the Baiyue and Dian tribes were eventually assimilated or displaced by the Han Empire. Evidence of Han dynasty influences are apparent in artifacts excavated in the Baiyue tombs of modern southern China. This sphere of influence eventually extended to various ancient Southeast Asian kingdoms, where contact led to the spread of Han Chinese culture, trade and political diplomacy. The increased demand for Chinese silk also led to the establishment of the Silk Road connecting Europe, the Near East, and China.
Background
Military campaigns against the Baiyue began under the Qin, the dynasty that preceded the Han. The First Emperor of the Qin craved for the resources of the Baiyue and ordered military expeditions against the region between 221 and 214 BC. He sent a large contingent of soldiers against Lingnan in 214 BC, comprising conscripted merchants and soldiers. Military garrisons were installed, the Lingqu Canal was constructed, and new areas were placed under Qin administration. The collapse of the Qin caused the dissolution of Qin administration in southern China. Indigenous Yue kingdoms emerged in the former Qin territories, including the Nanyue kingdom in Guangxi, Guangdong, and Vietnam, Minyue in Fujian, and Eastern Ou in Zhejiang.
Supported by the Han military, Minyue was established in 202 BC and Eastern Ou in 192 BC after the fall of the Qin dynasty. Zhao Tuo, a former Chinese commander of the Qin, established Nanyue in 208 BC after the death of the emperor Qin Shi Huang. Emperor Gaozu, first emperor of the Han dynasty, approved Zhao Tuo's new title as king. Zhao was born in the city of Zhending in Central China, and the ruling class of the new kingdom was composed of Chinese officials from the former Qin dynasty. In 180 BC, Zhao offered to submit as a vassal state and the Han accepted, a decision partly based on his family's northern Han Chinese ancestry.
Military campaigns
Campaigns against Minyue and Eastern Ou
Military campaigns were launched against the Baiyue under the reign of the Han emperor Wu. The Eastern Ou Kingdom requested Han military assistance when Minyue invaded the kingdom in 138 BC. Supreme commander Tian Fen opposed Han intervention. Tian told the emperor that the Yue tribes could not be trusted. Battles between the Yue tribes occurred frequently, and Tian believed that protecting them was not a responsibility of the Han court. The Han official Zhuang Zhu convinced the emperor to intervene in the war. Zhuang's argument was based on the emperor's role as the Son of Heaven, a concept in Chinese political philosophy. In Sima Qian's Records of the Grand Historian, Zhuang is reported to have said:
The only thing we should worry about is whether we have strength enough to rescue them and virtue enough to command their loyalty... Now a small country has come to report its distress to the Son of Heaven. If he does not save it, to whom can it turn for aid? And how can the Son of Heaven claim that the rulers of all other states are like sons to him if he ignores their pleases?
The Minyue surrendered after a Han naval force led by Zhuang Zhu was dispatched from Shaoxing in northern Zhejiang, and withdrew from Eastern Ou. The Yue tribes of Eastern Ou were transferred to the north, between the Yangtze River and Huai River.
A second intervention was launched in 135 BC after Minyue, ruled by Zou Ying, invaded Nanyue, ruled by Zhao Mo. Nanyue had been a Han vassal since 180 BC. Zhao asked the Han for their support, and the emperor responded by sending an army led by Wang Hui and Han Anguo against Minyue.
Zou Ying was assassinated with a spear by his younger brother Zou Yushan, who plotted against the ruler with the royal family and prime minister. Ying beheaded the corpse and gave the head to a messenger, who delivered it to Wang as a sign of Minyue's surrender. After the assassination, Minyue was succeeded by a state divided into a dual monarchy composed of the kingdom of Minyue, controlled by a Han proxy ruler, and the kingdom of Dongyue, ruled by Zou Yushan.