The three headed elephant is of Buddhist/Hindu origin (Airavata or Erawan). The symbol was used in the Kingdom of Laos flag. The three heads of the elephant came to represent each of the former small kingdoms of the Kingdom of Laos: Vientiane, Luang Prabang, and Xieng khouang or Champassak.
In Laos? history the Three-head elephant started to appear about eighteenth century due to the separation of three smaller countries from Lan Xang in Laos.
The three head elephant is the symbol of three major Gods in Buddhist/Hindu mythology: BRAHMA, VISHNU AND MAHESH. Among the three of them, the creator is Brahma, the keeper is Vishnu, and the destroyer is Mahesh.