The Yi share common ancestry with other ethnic groups such as the Bai, Naxi, Lahu, and Lisu of Yunnan, and seem also to be related to the Di and Qiang peoples of western Sichuan. Between the second century B.C. and the early Christian era, the forerunners of the Yi made their appearance in the areas of Dianchi (present-day Kunming) in Yunnan and Chengdu in Sichuan. After the third century AD. Their activities were extended to northeastern and southern Yunnan and into northwestern Guizhou and Guangxi. Present areas of settlement are shared with a number of different ethnic groups, including Miao, Lisu, Hui, Hani, Dai, Zhuang, and Tibetans. There has also been a long history of interaction with neighboring Han people; Han systems of agriculture influenced the Yi in some areas. Much of the Yi area of settlement was governed indirectly by the Chinese state, through appointment of local Yi. Nobility as rulers. Some Yi families became powerful landlords. Before 1949, many Han people were captured or purchased to become slaves in Yi communities. At the same time, the trade between Han and Yi developed, with the Yi exchanging medicinal materials, furs, and other local products for salt, cloth, and iron provided by Han merchants. In the nineteenth and early twentieth centuries, the Yi were engaged in the opium trade. After 1949, Han and other ethnic groups migrated into the Yi areas. Many modern techniques of farming and stock raising were introduced, as were changes in general life-style. As a result, local industries and enterprises, as well as science, education, and cultural developments have been strongly promoted.