"It's tradition," came the shrugged reply from our French guide Remy when I gingerly enquired why we were riding young Berber and Arab stallions that had clearly not seen a female for many months.
"In Tunis you can ride mares and geldings like in Europe, but down here we still do things the old way," he added as Massoude - which means 'lucky' in Arabic - snorted and reared under me on the soft sand of the Sahara.
From Nefta, in the south-west of Tunisia, we walked, trotted and cantered through gently rolling dunes with desert birds wheeling overhead. A stiff sandy breeze on our backs kept us cool.
We came across a donkey-mounted shepherd and his flock of 200. "A goat or a sheep is worth a month's salary," explained Remy, "so this flock belongs to a very wealthy man. You can buy a house for 100 goats."
But with Massoude snorting beneath me, I couldn't help being distracted by the idea that the donkey might be female. I held on tight but in the end - perhaps it was the stiff breeze - he didn't notice and we were off chasing a cantering gang of camels.
With only the sound of the wind howling in our ears, manes and turbans, our troop seemed as timeless as the desert sand our horses' hooves were clambering through.
A few hours on, Massoude and the other horses panted up a steep incline. In front of us lay perfectly reposed dunes. Gullies of white sand rippled across the desert floor like swirling horses racing towards the large white setting sun.
In a last dash, we raced to meet the jeeps at Laariguet. Sci-fi fans recognise it as Mos Espa - it's still preserved much as it was when it served as a set for Star Wars: The Phantom Menace, where Darth Maul had his spat with Liam Neeson (as Qui-Gon Jinn). Emerging from the swirling sandstorm the orb-shaped homes made a surreal end to our first day.
In the jeeps on the way back to the hotel we stopped off at Ong Jemal, to see where Ralph Fiennes crash-landed his plane in a desperate bid to save his lover Kristin Scott Thomas in The English Patient.
The next morning, with Massoude now into his stride, we were trotting through the canyons of the eastern tail of the Atlas Mountains. Cake layers of brown, orange, red, yellow and pink stone surrounded us. The still air was disturbed only by the sound of our horses' hooves crunching over stone. Soon the canyon opened up to reveal a sprawling, stony desert landscape. In the distance I expected to see the silhouette of Butch Cassidy and the Sundance Kid lolloping into view.
We'd planned to eat lunch in the open but by mid-morning we were riding through a steady rain. Being Tunisia, it didn't take long to find a family who happily handed over their home to us.
By noon, with Massoude and the other horses under dripping trees outside, we were huddled around a gas flame with our cook Aziz toasting caraway seed bread. Remy explained we would have to keep our wine under wraps.
"If we ask the man of the house he will agree because his sense of hospitality will require him to," he said, "but then he will have fallen out with his God - and will have to make many prayers to repent."
Uneasy with this logic but in need of a drink, we sheepishly held out our glasses for the illicit cure as our unseen host recited his afternoon prayers in a nearby room.
Refreshed, we set off along a normally dry riverbed, now swollen by the rain. We encouraged our horses through swirling eddies until even the bravest would not go forward. Down we waded, waist-deep, until we were able to reach a mountain road. "It's all part of the adventure," laughed Remy from under his cowboy hat.
Day three, and after a few miles we were faced with a steep and rocky mountain. "We will lead our horses on the guide ropes," said Remy. For the next 3km we clambered ahead of our horses, zigzagging up a vertiginous incline. Then we were on board again and crunching across a boulder-strewn mountainscape until we were around 800m above sea level and overlooking the land across which we had ridden for three days. Salt lakes, sand and mountain stretched under the setting sun.
"I love to work with horses," said Remy. "I live to share this landscape with people who love horses and love riding."
As the sun seeped away to the west and I stepped down from Massoude for the last time, I listened to his contented snuffling and imagined the life that nomads shared with these horses for thousands of years.
The author travelled with Siroko Travel
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