The Han conquest of Dian was a series of military campaigns and expeditions by the Chinese Han dynasty recorded in contemporary textual sources against the Kingdom of Dian in modern Yunnan. Dian was placed under Han rule in 109 BC, after Emperor Han Wudi dispatched an army against the kingdom as the empire expanded southward.
Dian was a kingdom in modern Yunnan, southwestern China. According to Han historian Sima Qian's Shiji, it was established by Zhuang Qiao, a general of Chu Kingdom during the Warring States period. He had been sent to the area as part of a Chu military campaign. When Chu homeland was invaded by the Qin, Zhuang Qiao stayed behind in Yunnan and established the Dian kingdom. The Qin was subsequently overthrown by the Han, and the commanderies of the new dynasty, Ba and Shu, bordered Dian.
The earliest Han expedition against the Dian Kingdom was led by Tang Meng in 135 BC, who established the Jianwei commandery in the region. Han dynasty observers saw Dian as a potential periphery that can absorbed by the empire beyond its frontiers. The Dian Kingdom was a major business center, linked by networks of prosperous trading routes to modern South and Southeast Asia. The trade connections were seen as attractive to the Han rulers as they desired to capture the areas prosperous maritime trade routes. These incentives motivated Emperor Han Wudi to attempt to extend the Han dynasty's control towards the Dian Kingdom to secure access to trade routes of various products such as silk and bamboo. Another incentive for the Han dynasty to expand against the Dian was the rich endowment of minerals and commodities such as iron, tine, silver, and lead that the territory of present-day Yunnan province offered. The Han had been attracted by the wealth of the kingdom, which traded cattle, fruit, horses, and slaves. Han soldiers opened up new trade routes, then expanded further north, toward an area near Shu. The commandery was later abandoned because of rising costs and the wars against the Xiongnu to the north of China. A later Chinese expedition, heading south to established a trade route after a report on Central Asian trade in 122 BC, was captured by the Dian for four years.
A military campaign dispatched by Emperor Han Wudi in 109 BC invaded and annexed the Dian Kingdom. Sinification of these peoples was brought about by a combination of Han imperial military power, regular Han Chinese settlement and an influx of Han refugees. The Yizhou commandery was established in the former kingdom. Dian's surrender was verified by archaeologists, who discovered an imperial seal inscribed by the Han for the king of Dian. There were a series of unsuccessful rebellions by the Dian against Han rule. The first two incidents occurred in 86 BC and 83 BC. A rebellion in 35 BC–28 BC was suppressed by Chen Li, governor of the Zangge commandery. More violence surfaced during Wang Mang's usurpation of the Han emperor and reign in 9–23. Wang responded by dispatching military campaigns against the southwest. One campaign lost 70% of its soldiers due to illness. Another, with 100,000 men and twice the amount of supplies, had little success.
There was also a rebellion in 42–45 and 176. During Emperor Mingdi's reign in 57–75, the Han expanded further, and established a new commandery in Yunnan, Yongchang, west of the former Dian kingdom in Yizhou. In 114, Dian tribes residing west of Yuexi/Yuesui Commandery accepted Han rule. Emperor Huangti embarked on a sinicization campaign during his reign between 146 and 168 that introduced Han Chinese ethics and culture to the Dian tribes. The process of assimilation of the Dian aborigines into Han Chinese culture was difficult as there were periodic rebellions from time to time. Rebellions and resistance were put down by the strong action of the Han dynasty's military superiority as the Dian Kingdom was eventually absorbed into the Han Empire. Conquered by the Han dynasty, Han Chinese settlers began moving into the lowlands once occupied by the Dian. Over the centuries, the Dian were assimilated by the Han Chinese and were virtually extinct by the 12th century AD.
The Dian were gradually displaced and assimilated into Han Chinese culture following the Han Empire's annexation of the Dian Kingdom in 109 BC. It is apparent in the artifacts uncovered by archaeologists in the area. Mirrors, coins, ceramics, and bronze items manufactured in the Han style have been found in modern Yunnan. Emperor Huangti encouraged and implemented the teaching of Chinese belief systems in Dian. Dian artifacts, once visually distinct from the Han, borrowed heavily from Han imports by 100 BC, indicative of Dian's assimilation into Han Chinese culture.