“Lao or Laotian” is the official language of Laos , and can be also found in the northeast of Thailand that we will called this language is “Isan”. History of Laos language began from the Lao language is descended from Tai languages spoken in what is now southern China and northern Vietnam because due to Han Chinese expansion, Mongol invasion pressures, and a search for lands more suitable for wet-rice cultivation, the Tai peoples moved south towards India, down the Mekong River valley, and as far south as the Malay Peninsula. Oral history of the migrations is preserved in the legends of Khun Borom.