The Great Pyrenees is also known as the Pyrenean Mountain Dog a truly ancient breed whose remains have been found in the fossil deposits of the Bronze Age (1800 to 1000 B.C.). The Tibetan Mastiff, brought to Europe from Asia, is the ancestor of the Great Pyrenees. This dog can still be seen working as a sheepdog in Europe. In the United States it has gained popularity as a household pet and companion dog.