Ethnic Lao, the principal lowland inhabitants and politically and culturally dominant group, make up the bulk of the Lao Loum and around 60% of the total population. The Lao are a branch of the Tai people who began migrating southward from China in the first millennium A.D. In the north, there are mountain tribes of Miao–Yao, Austro-Asiatic, Tibeto-Burman - Hmong, Yao, Akha, and Lahu who migrated into the region in the 19th century. Collectively, they are known as Lao Sung or highland Lao