The Âu Việt or Ouyue were an ancient conglomeration of Baiyue tribes living in what is today the mountainous regions of northernmost Vietnam, western Guangdong, and northern Guangxi, China, since at least the third century BCE. They were believed to have belonged to the Tai-Kadai language group. In eastern China, the Ouyue established the Dong'ou or Eastern Ou kingdom. The Western Ou were other Baiyue tribes, with short hair and tattoos, who blackened their teeth and are the ancestors of the modern upland Tai-speaking minority groups in Vietnam such as the Nùng and Tay, as well as the closely related Zhuang people of Guangxi.