Truly an ancient and majestic breed, the Pyrenean Mountain Dog was even proclaimed the Royal dog of France by Louis XIV. Some believe the breed was developed by Basque herdsmen, while others find its ancestry in the great white dogs of Asia, but there is little doubt that the breed's primary ancestors are the Abruzzese Mastiff and the Mastin Espanol, themselves descended from the ancient Molossers of the Balkans, Caucasus and Central Asia. However, thanks to the relative isolation of the region and strict breeding practices based on established working qualities and physical features, the Great Pyrenees has been a pure breed for at least 1500 years, if not longer. This French breed should not be confused with the Spanish Pyrenean Mastiff. They're closely related, but these are very different breeds. An excellent protector of shepherds and their flocks, this breed has traditionally been used as a guardian of farms, as well as a milkman's cart-pulling dog. In its homeland, the Great Pyr is primarily a valued wolf-killer, often employed alongside the smaller Pyrenean Sheepdog, an energetic herding breed that also serves as an alarm dog announcing the presence of predators. Tracing its roots back to the old Eastern Molossers, the Great Pyrenees is a typical mountain dog, resembling many similar working breeds found worldwide. Although it may seem like a big fluffy teddy-bear, this is a rugged and fierce Moloss which takes its work very seriously. Like some other ancient shepherd breeds, the Great Pyr seems somewhat sluggish when moving with the herds, but it is a very agile and convincing protector when needed.

The Lourdes Shepherd Club was formed in France and the first breed Standard was written in 1907. Two years later, the Great Pyrenees was introduced to Great Britain, where it became a popular companion and Show dog, which it remains to this day. As the breed was flourishing in England, the quality of the French specimens has slowly been deteriorating and in the 1920, a preservation society was established under the name "Reunion des Amateurs de Chiens Pyreneans" by Senac LaGrange and fellow breed enthusiasts, who also wrote a new Standard in 1927. The Great Pyrenees was recognized by the American Kennel Club in 1933, only two years after the Crane family of Needham, Massachusets imported their first Pyrs for their newly established breeding programme, becoming the first breeders of this great Molosser in the United States. The breed has enjoyed great popularity all over the globe and can be commonly seen at Dog Shows worldwide, as well as a common pet and watchdog. It should be noted that the modern incarnation of the breed shows some variety, primarily between the indegenous working examples and their Dog Show counterparts. Even among the Show group, there is a noticeable difference between the French, British, German and American specimens. Some fanciers claim that the American bloodlines in particular look uncharacteristic and the influx of other white breeds, such as the Akbash and Kuvasz is suspected. Whether this is true or not, the appearance of American dogs is noticeably different and allows for greater variety than the French Great Pyrenees population. However, due to the common trade between continents and countries based on the Show achievements of certain strains, the so-called American type can also be seen in many European countries. However, while the appearance of American dogs is not up to everyone's liking in Europe, as a working livestock guardian the Great Pyrenees is at the very top in popularity in the United States, with the American bloodlines viewed as much superiour to any imported variety.

Its imposing size makes the Pyrenean Mountain Dog better suited for rural surroundings than for an urban environment. Still, it's a popular breed that can be found in cities throughout the world, due to its wonderful personality and temperament. However, bloodlines that are bred strictly for work are known to be more aggressive towards strange people and dogs, although not to the extent of some other LGD breeds. The Great Pyrenees is intuitive, alert and reasonably territorial, making a capable watchdog. Broad-chested, well-boned and agile, this magnificient mountain dog is truly an impressive Moloss, both in appearance and personality. One of the most attractive attributes of the Great Pyr is its profuse coat. Although uniform white/ivory is preferred, the most common colouring is white with patches of pale yellow, wolf gray and even red markings, known as "badger patches", usually found on the head. The average size is around 30 inches.