When Muk Yeun Ching discovered that Deun Yu's mother was Muk's own teacher/mother's mortal enemy Do Bak Fung, Muk noted that Do was an ethnic Bai. Do then went on to explain that she was indeed Bai, and therefore her son Deun Yu was half Bai.
That remark means that the Deuns of Dali were not themselves Bai. Were the Deuns Han Chinese?