The origin of animals were imported in the 90th. There was never any exact details where the animals coming from. It is expected that this is the Malay Sub-species of animals, which lives from the southern part of the Strait of Kra.
Unfortunately, the DNA study which should confirm this were stopped without success, because it was not possible to insulate the DNA does of museum samples. So it can no one say with certainty whether they are pure animals.