It literally indicates the "midland Lao", and comprises a variety of different ethnic groups of mostly Austro-Asiatic origin.

Lao Theung are largely of Mon-Khmer stock, and are believed to be the autochthonous population of mainland Southeast Asia, having migrated south in pre-historical time.

Their legendary origin is related in the "Pumpkin Story" in James McCarthy's account of 1894.

Although they now live in the higher uplands of Laos, they were originally paddy rice farmers, until displaced by the influx of Lao Loum migration into southeast Asia from Southern China.

[1] Midland Lao still have a lower standard of living than other ethnic groups.