Dian (Chinese: 滇) was an ancient kingdom established by the Dian people, a non-Han metalworking civilization that inhabited around the Dian Lake plateau of central northern Yunnan, China from the late Spring and Autumn period until the Eastern Han dynasty. The Dian buried their dead in vertical pit graves. The Dian language was likely one of the Tibeto-Burman languages. The Han Empire's annexation of the Dian kingdom in 109 BCE eventually led to the establishment of the Yizhou commandery. Dian culture started from at least the 8th century BCE, until it fell under the control of the Han dynasty in 109 BCE.

Dian was an ancient kingdom situated in modern Yunnan, southwestern China, in the region around the Dian Lake. According to Han historian, Sima Qian, it was established in 279 BCE when King Qingxiang of Chu sent a military force to the southwest. Zhuang Qiao, a general of Chu, reached the Dian Lake as part of the Chu military campaign. When the Chu homeland was invaded by the Qin, Zhuang Qiao decided to stay in Yunnan and adopt the native ways, establishing the Dian kingdom. The Qin dynasty was subsequently overthrown by the Han, and the commanderies of the new dynasty, Ba and Shu, bordered Dian.

According to the Shiji, the southwest was dominated by barbarians, among whom the ruler of Yelang was the most powerful. To the west of Yelang were the Mimo and the most powerful among them was the ruler of Dian. North of Dian was Qiongdu. All these people styled their hair in a mallet-shaped fashion. These were settled peoples who worked the fields and lived in settlements.

In the area from Tongshi east to Yeyu were the Sui and Kunming tribes who braided their hair and moved from place to place with their herds. They had no fixed abodes or rulers. Northeast of the Sui were the Xi and Zuodu. The most powerful of the Zuodu were the Ran and Mang, who lived west of Shu. Some of them moved from place and place but others lived in fixed abodes. Northeast of the Ran and Mang were the Baima, who belonged to the Di tribe.

Shu is the only place that makes ju berry sauce. large quantities of it are exported in secret to the markets of Yelang, which is situated on the Zangke. The Zangke at that point is over 100 paces across, wide enough to allow boats to move up and down it. The king of Southern Yue sends money and goods in an effort to gain control of Yelang, extending his efforts as far west as Tongshi, but so far he has not succeeded in getting Yelang to acknowledge his sovereignty.

— Shiji

In 135 BCE, the Han envoy Tang Meng brought gifts to Duotong, the king of Yelang, which bordered Dian, and convinced him to submit to the Han. The Jianwei Commandery was established in the region. In 122 BCE, Emperor Wu dispatched four groups of envoys to the southwest in search of a route to Daxia in Central Asia. One group was welcomed by the king of Dian but none of them were able to make it any further as they were blocked in the north by the Sui and Kunming tribes of the Erhai region and in the south by the Di and Zuo tribes. However they learned that further west there was a kingdom called Dianyue where the people rode elephants and traded with the merchants from Shu in secret.

In 111 BCE, Emperor Wu of Han ordered the barbarian tribes of Jianwei Commandery to raise troops for the campaign against Nanyue. Fearing that neighboring tribes would attack them in the absence of their men, the tribe of Julan rebelled against the Han and killed the governor of Jianwei Commandery. After Nanyue was defeated, Han forces turned north and subjugated the various tribes of Yelang, Julan, Toulan, Qiong, Zuo, Ran, and Mang.