Over millions of years primitive breeds of horse migrated from their North American homeland to the Old World across the Bering land-bridge which used to connect Alaska and Siberia where the Bering Sea is now. The last single-toed representatives of the genus Equus also took this path and while their relatives in North America mysteriously died out about 10,000 years ago they themselves spread out over Asia, Europe and Africa and evolved into the familiar shapes of the present-day zebras, donkeys and wild horses.

Among the wild Equidae, the original horses had probably the largest area of distribution. During the Ice Age they were able to survive under the most diverse living conditions' on moor and horse including Arabs. The Norwegian fjord horse has retained most of the qualities of the original colouring.

In the mountainous regions of north west Africa a comparatively large but very lightly built horse evolved. Its tapering head with swelling muzzle and the unusual distance between the eyes and the nostrils give it a very striking appearance.

These Barb horses characterized by their amazing stamina and sure-footedness have been cross-bred with Arabs, but basically they trace their descent from the desert mountains breed. The Islamic conquerors took the horses with them to south-west Europe and used them as the basis for breeding the noble Andalusian horse which in the Baroque period was much prized throughout the whole of Europe.

On the stud farms belonging to the nobility the Andalusian was then used as the basis for developing such famous breeds as the Neapolitan, Lipizzaner, Frederiksborger, Knabstruppper and Klanruber. The American Mustang and, through them, the Western breeds of horse are also descended from these Andalusians.

Finally a fourth basic type, a small graceful finely-boned almost gazelle-like horse evolved on the bleak expanses of the deserts of south-west Asia. As the grasses which thrived in their native habitat were not very lush, though they were nourishing, this breed of horse did not need either particularly large or long teeth or very capacious digestive organs. There were no hiding places on that open terrain, so a quick escape was always the best protection from hostile predators. With a fiery temperament which guaranteed a lightning reaction to danger and a broad thorax allowing plenty of room for efficient lungs and a strong heart, more than any other tundra, in forests, mountains, steppes and desert-like regions. Both their bodily structure and their natures were shaped by the climate, vegetation, and condition of the ground. In the course of several generations different breeds of geographical subspecies of horse evolved from having to adapt to these varying conditions, particularly where the isolated living conditions of individual populations prevented any further exchange of genes.

There were at least four main types as well as numerous hybrids. On the moors and glacial landscapes of the northern tundra a tough sturdy little f horse eked out a bleak existence. This primitive pony had a broad rump which, allowed plenty of room for the robust r digestive organs, long teeth specially designed to cope with being constantly worn down by grinding, and strong masticatory organs which enabled it to feed on tough stringy plants, lichen and , even the bark of trees. Doubtless it also, had a coarse fatty coat and a luxuriant l mane and tail. The northern ponies are f descended from this type which the [naturalist called Equus prewalskii gracilis.] Most of the domestic breeds of pony retained their essential characteristics despite being cross-bred with other breeds, but only the Exmoor pony of south-western England has remained pure-blooded since the Ice Age.

A large massive horse with a heavy head also lived in the north alongside this small agile pony. It too could survive on large quantities of poor food, and certain subspecies reached a withers height of about 180 centimetres. This was Equus prewalskii robustus, said to be the founding father of all the cold-blood breeds, even though these too have been C:ross-bred with other domestic breeds of breed of horse this desert type was built for speed. The Arabs inherited this legacy and it is an indisputable fact that the breeding of warm-blood horses throughout the world would be unthinkable without their contribution.

Hybrid animals which were spread over much larger areas and were less highly specialized, not having had to adapt to such extremes of living conditions, were naturally domesticated much more frequently than any of the four main types. Thus Prjevalsky's horse, a steppe type, which fits in somewhere between the cold-blood breeds and the desert type, was the origin of numerous Asiatic breeds of horse.

Mongolian ponies, for example, have retained many of its qualities. However this, the last of the wild horses, is definitely not, as is often claimed, the founding father of all domestic horses. In addition to other breeds of primitive horse, the tarpan, which was spread over Central and Eastern Europe, played a particularly important role in the development of the domestic horse. These forest and steppe horses provided the basis for the breeding of warm-bloods in Europe and it is very likely that they were the first horses to be domesticated.

The native habitat of both the small primitive pony and the massive ancestors of the cold-blood breeds was the glacial landscapes, moors and heaths of the northern tundra.