The Tibetan Terrier is believed to be a progenitor of later dog breeds, including the Shih Tzu. The breed is thought to have been cultivated about 2000 years ago, by Buddhist monks. The Tibetan Terrier is thought to be the progenitor of several other popular dogs, among them, the Shih Tzu, the Lhasa Apso, and the Tibetan Spaniel.