The Lao is an ethnic subgroup of Tai/Dai in Southeast Asia. The etymology of the word Lao is uncertain, although it may be related to tribes known as the Ai Lao who appear in Han Dynasty records in China and Vietnam as a people of what is now Yunan Province. Tribes descended from the Ai Lao included the Tai tribes that migrated to Southeast Asia. The English word Laotian, used interchangeably with Lao in most contexts, comes from French laotien/laotienne. The Lao people, like many other Tai peoples also refer to themselves as Tai and more specifically Tai Lao. In Thailand, the local Lao people are differentiated from the Lao of Laos and by the Thais by the term Thai Isan, a Sanskrit-derived term meaning northeast, but 'Lao' is still used.
Contributions by Nintala, Henry Flower, and Kborland.