It is highly doubtful that the Tibetan Mastiff is the ancestor of all Molossers, but this popular myth is still widely spread today. More likely to be descended from early Euro-Asian breeds, the Tibetan Mastiff shares its name with quite a few breeds, mostly of Himalayan origin. The popular name for the Tibetan Mastiff is Do-Khyi, meaning "Tied Dog", although many different types exist, like the Naj-Khyi, Dzy-Khyi, Sgo-Khyi, Tsang-Khyi and others, differing in size, coat and temperament. As mentioned above, even some breeds that aren't just types of the Tibetan Mastiff are often lumped under this name, like the Amdo Mastiff, Bhotia, Bangara, Kunlun, Khonch Nokhoi, Shan Mastiff, Kham Sheepdogs and many others. There is also a bearded variant of the Tibetan Mastiff, called Kyi-Apso. However, the Do-Khyi is the most popular type of the breed and is commonly considered to be the "real" Tibetan Mastiff in the West, even though its true origin is anything but native.
With the recent interest of American and European breed fanciers in Chinese-bred Tibetan Mastiffs, the impact of somewhat authentic bloodlines is becoming more noticeable in Western stock, but it should be noted that the modern Tibetan Mastiff is a European creation and not an indigenous Tibetan breed. Descended from a limited stock of various Asian and eastern-European dogs imported to Britain in the late 1800's, the breed was developed in England, with its Standard written in the 1930's. In its ancestry it counts as strong of an influence of English Mastiffs, Newfoundlands and Saint Bernards as it does that of authentic Asian dogs. Although many historical accounts of giant ferocious black and black-n-tan dogs were assumed to had been descriptions of Tibetan Mastiffs and have been used to substantiate the breed's claim to antiquity, the truth of the matter is that such attitude has much more to do with the desires of the Tibetan Mastiff's fans than with reality.
From the initial descriptions of powerful livestock guarding, property protecting and large game hunting dogs which measured 35 inches at the shoulder to the mighty wardogs brought to the Balkans by Alexander the Great and fierce Roman arena performers, these then-called Indian Dogs which were assigned the Tibetan Mastiff name eventually became massive, yet short Newfoundland-like animals which were likened to black Saint Bernards and "wooly" English mastiffs by the time the British and western-European dog fancy became interested in breeding and promoting them. It is much more likely that those early accounts were describing the original Sylvan population and its various proto-Molossian subtypes derivatives than the large Chow-type animals that the true dogs of Tibet and the Himalayas really were and still are in their indigenous form. Some would even go as far as to claim that the dogs regarded as native Tibetan Mastiffs were nothing more than random crosses between the Sylvan and the Chow, but such statements are obviously not appreciated by those who choose to believe the "official" versions of the breed's origin.
There is so much romanticizing and propaganda involved with the Tibetan Mastiff, but it is very clear that the overwhelming majority of the breed's supposed history has been fabricated for simple marketing purposes by its true creators, these being the English, Swiss and French cynologists, whose "product" eventually became so appealing worldwide that even the Chinese breeders decided to jump on the bandwagon and promote their poorly bred mastiffs as the oldest and most valuable breed of dog on the planet, as is reflected in ridiculously high prices they've been demanding for their dogs from naive westerners in recent years.
Regardless of its true heritage, the ever-popular Tibetan Mastiff is an independent, reserved and aloof Molosser, protective and fairly territorial, although seemingly lethargic. The American and European bred Do-Khyi dogs are not quite as aggressive as the Asian ones, making the Western bloodlines more suitable for companion life. Although there is still a great variety of sizes within the breed, the preferred type of the modern Do-Khyi has a large, broad head, a powerful neck, a tightly curled tail and its heavily-boned, loose-skinned and massive body is fairly muscular.
While not the most athletic Molosser, the Tibetan Mastiff is quite an attractive breed, with a rich and thick coat, most commonly black-and-tan in colour, usually with white markings on the chest, but other colours exist, like black, brown, fawn, gold, blue and grey, with or without the tan points. The average height is around 27 inches.