Yelang 夜郎 was a native kingdom located in the border region between the provinces of Yunnan, Guizhou, Guangxi, and Sichuan, and flourishing between the late Warring States 戰國 (5th cent.-221 BCE) and the late Former Han period 前漢 (206 BCE-8 CE). The people living in this state belonged to an ethnic group by the Chinese called Pu 濮. The state consisted of several territories controlled by chieftains, of which that of the Yelang was the strongest. The tribes lived on agriculture and pasturage, but also of hunting. They believed to be descendants of a "bamboo king" (zhuwang 竹王). As a burial custom, the heads of the dead were covered by a bronze kettle (taotouzang 套頭葬). Tombs discovered in Weining 威寧 included pottery inscribed with signs, perhaps a kind of script.
During the Warring States period, the state of Chu 楚 sent an embassy under Zhuang Qiao 莊蹻 to the state of Dian 滇 in Yunnan which passed the territory of Yelang. Impressed by the army of Chu, Yelang accepted the domination of Chu.
During the reign of Emperor Wu 漢武帝 (r. 141-87 BCE), Yelang presented tributes to the Han court, but did not accept Chinese suzerainty. Emperor Wu desired to conquer the territory, but Tang Meng 唐蒙 suggested to establish formal relationship, and Tang was sent to visit the lord of Yelang, Duotong 多同, who accepted investiture as a formal official of the Han empire. In 135, the Han created the commandery of Jianwei 犍為 that partially controlled Yelang territory. In 126 CE, Gongsun Hong 公孫弘 (200-121 BCE) suggested to give up plans of colonizing the southwest, but Emperor Wu had the districts of Yelang and Qielan 且蘭 created and appointed a Commander-in-chief (duwei 都尉) to care for peace and order in the region.
In 122, Zhang Qian 張騫 (c. 164-114) returned from his Inner Asian journey and reported that he had seen in the country of Daxia 大夏 (Bactria) cloth from Shu 蜀 (Sichuan) and bamboo tools from Qiong 邛 and thus learnt that there was an economic route between southwest China and Bactria via Shendu 身毒 (India), which means there was an alternative to the trade route of the Silk Road in the north. Emperor Wu thereupon sent an embassy to the kingdom of Dian to make investigations about the trade route. He found that the rulers of Yelang and Dian were quite convinced that they were more powerful than the Han empire – an occurrence from which a famous proverb originated, saying "Yelang believes itself larger than it is" (Yelang zi da 夜郎自大).
Commodities from Shu like betel (jujiang 枸醬) also crossed Yelang territory to be brought to Fanyu (today's Guangzhou). From 129 on the Han empire built roads and postal stations in the region. Sima Xiangru 司馬相如 (179-117 BCE) once visited the country as pacification commissioner (fengshi xuanfu 奉使宣撫).
In 111 BCE finally, after the termination of the independent empire of Southern Yue 南越, the Han armies invaded and conquered Yelang, and its lord was forced to visit the Han court, where he was formally invested as King of Yelang and given a seal. In the late years of the Former Han period, the king of Yelang, Xing 興, rebelled against Han suzerainty. In 27 BCE, Chen Li 陳立, the governor (taishou 太守) of Zangge 牂牁, had him executed, but Xing's son Yewu 邪務 and his father-in-law Wengzhi 翁指 continued the resistance against the Chinese colonial policy until they were defeated, too.
The ruling elite of Yelang is believed to be ancestors of the national minority of the Yi 彝族, even if a territory as vast as the state of Yelang also included other tribes.
A linguistic study of Wade (2009) demonstrated that the Sanskrit term for China, Cīna, is quite probably derived from the proper native pronunciation of the name Yelang, ʐi-na. The existence of the trade route to India supports this assumption.