 There is generally few written records available in Ersu, therefore not much is known about the history of the people who spoke it.While it has been theorized that the Ersu people moved from Tibet, or were from neighbouring ethnic groups such as the Yi, there is some evidence that the Ersu predated even the Yi in settlement in that area.The Yi people who moved during the Tang Dynasty to the regions near where the Ersu resided documented the Ersu as "the aboriginals".