The Ersu are officially part of the Tibetan nationality, but in the 1980s they asked the government to create a new minority, called the Xifan, and to include them under it. The authorities declined. The linguist Sun Hongkai says, "Ersu speakers at different localities have different autonyms: those living at Ganluo, Yuexi and Hanyuan call themselves Ersu, Buerzi or Ersubuerzi; those living at Shimian use Lusu, and those living at Muli, Jiulong and western Mianning Lisu. These different autonyms are dialectal variants of the same word, originally meaning 'white people'."
Regardless of where the Ersu may have originated, it is known that they have lived in their present location for many centuries. Qiang nomads once ruled western China as far as today's Inner Mongolia. Gradually their kingdoms broke up and they migrated south and west. The present official Qiang nationality in China only represents a fraction of the original Qiang race. Most were assimilated by larger groups long ago.
Culturally, the Ersu have been swallowed up by the Tibetans. Almost every aspect of their lives reflects their belief in Tibetan Buddhism.
The Ersu believe they will be reincarnated when they die and will come back to the earth as a person in a higher social position if they have lived a virtuous life. They will come back as an animal if they lived a wicked life. This belief results in the Ersu having little motivation to help the afflicted among them, as suffering is considered the consequence of a person's bad karma.
There has never been a known church or Christian among the Ersu. The Border Mission of the Church of Christ in China and the American Baptists worked among the related Jiarong people until 1949, reporting 34 converts in 1934. No outreach, however, was ever undertaken to the Ersu.