Inhabiting mainly lowland river valleys the Lao, Phouthai and other Tai-speaking peoples are the main ethnic groups in Khammouane. There is also Mekong or Bru people, a Mon-Khmer-speaking ethnic minority that make up 13% of the provincial population. In smaller numbers are the Kri, Nguan, Atel, Themarou, and Maleng who are mainly found in the mountainous eastern part of the province.