Their galloping stocky, sandy-brown silhouettes inspired dreamy pre-historic cave paintings.
Now, an ancient species known as Przewalski's wild horse has narrowly avoided extinction thanks to zoos worldwide and is cautiously being re-introduced to its homeland on the vast Mongolian steppe.
In charge of keeping the world genealogy book for this rare species, the Prague zoo has played a key role in this historic homecoming.
"Three mares and one stallion have been acclimatising in the Mongolian province of Khomiin Tal since June," said zoo director Miroslav Bobek.
"We expect to move another four horses in 2012," he added.
For decades, Prague zoo has been breeding these sturdy animals which have survived in captivity since the last wild horse was seen in Mongolia in 1969.
More than one-third of some 1,800 Przewalski horses living all over the world today, including 1,600 in captivity, are related to horses bred at the Prague zoo.
Characterised by thick necks, large heads and stocky barrels, Przewalski's horses weigh between 250-350 kilograms (551-771 pounds), are about 1.2-1.3 metres (3.9-4.3 feet) tall at withers and two metres long.
To kick up the dust on the land of their ancestors, the horses spend about 30 hours inside special containers aboard a Czech army plane and then a lorry.
The newcomers to Mongolia -- a young stallion named Matyas and particularly the mares named Kordula, Lima and Cassovia -- have already attracted the interest of the denizens of the Khomiin Tal provincial wildlife reserve in western Mongolia.
An earlier group of Przewalski horses were brought to the province six years ago from another location in Mongolia by Takh, a French association bearing the Mongolian name of Przewalski's horses.
"One dominant stallion, Carex, jumped over the fence into the acclimatisation enclosure and joined the (new) group," Bobek said.
"He started to harass Matyas, but he soon had to face the competition of another 'jumper', a stallion named Bo, who turned out to be an even stronger natural leader," he added.
"Bo is an abbreviation of 'Born to be Wild', so he's doing credit to his name," Bobek said in an interview with AFP, shortly after he had returned from Mongolia.
"We hope that the arrival of our young horses will provide new stimulus to reproduction in the group in Khomiin Tal," he added.
With ancient cave paintings in Lascaux, France, featuring wild horses eerily resembling the Przewalski variety, the species is thought to have lived in Europe 20,000 years ago but climate change chased the animals away to Asia.
Europeans only encountered the wild horses at the end of the 19th century when Russian explorer and geographer Nikolai Mikhailovich Przewalski (1839-1888) discovered the animals in mountains bordering on the Gobi desert.
In the 20th century, hunting brought Przewalski's horses to the verge of extinction.
Today's survivors all hail from a group of 12 reproducers, said Bobek.
In 1959, Prague zoo spearheaded an international symposium focused on saving the wild horses.
Different zoos and foundations then kicked off programmes to exchange the reproducers and expand their population.
In the 1980s, when the number of Przewalski's horses bred in captivity reached 500, experts started reintroduction programmes.
Four other animals will leave Prague for Mongolia next year -- a herd that will undoubtedly comprise another three mares and one stallion.
"The horses live a harem life with a stallion inseminating several mares," said zoologist Jaroslav Simek, deputy head of the Prague zoo.
He hopes that young Matyas -- ruthlessly cornered by his rivals in Khomin Tal this summer -- will soon assert his authority.
"To a great extent, this depends only on himself, on his ability to attract mares and to create his own harem," Simek added.
Explore further: Purring tempo, sliding notes grab cats' attention