There are no yaks in Derbyshire - which rather upsets Phil Wallace, graphics teacher at Northampton school for girls. He has just spent his half-term holiday dressed as a Mongol warrior, chasing non-existent yaks across the hills and dales of the Peak District.

This idiosyncratic backpacking trip is a highlight for the fantasy role-playing group to which Mr Wallace belongs. For a week, 15 adults dressed as 12th-century Mongols battled, postured and trekked through the hills.

“We’re quite nomadic,” he said. “Not city types at all. So we were looking for nomadic characters. And we liked that Mongolians were also warriors, and that they had shamanistic, animalistic religions.”

The costumes are based, not on contemporary Mongolian felt overcoats, but on leather armour, worn under thick cloaks, which emulate the 800-year-old dress of Genghis Khan and his warriors. “They’re very comfortable and easy-to-wear,” he said. “And they’re warm and waterproof. People ask for a photograph with you all the time. I must be in so many photo albums.

“But the costumes are actually really good for February. Last year, it was -9xC. Our water bottles froze, and there was frost inside our tents. It’s battling against the extremes, isn’t it? That’s very Mongolian. It’s the way they’ve led their lives for centuries, at one with nature.”

Mr Wallace and his fellow warriors have compromised by sleeping in tents, rather than the traditional Mongolian felt-and-wood ger (“it would be a bit impractical when you’re backpacking,” he said). Nor do they eat Mongolian food, or drink traditional mare’s-milk alcohol. This, however, is for want of available mares for milking, rather than lack of will.

But the Peak District walks are merely preparation. Eventually, the group would like to visit Mongolia. There they would learn to ride horses, cook traditional stir fries and shoot bows and arrows, before embarking on a trek across the Mongolian steppe.

And, while they are there, two members of the group hope to get married, in a full-scale Mongolian ceremony. For some clans, this includes trained archers galloping past on horseback. Others traditionally include a full-scale brawl between the bride and groom’s families. Groom Mick Collins, a drama teacher at Sidney Stringer comprehensive, in Coventry, is undaunted by the possibility of a punch-up with the in-laws.

“Mongolian life is very hands-on,” he said. “It’s a hands-on way of passing on knowledge which is just like drama lessons. And they don’t have a word for ‘stress’, which appeals to me as a teacher. It’s a culture that is special to us. So I won’t mind toasting my nuptials with a glass of mare’s milk.”

Neither teachers tries to hide their eccentric hobby. Mr Wallace says pupils at his comprehensive appreciate the appeal of playing a 12th-century Asiatic marauder. “Since the Lord of the Rings films came out, teenagers have been more aware of fantasy worlds,” he said. “They’re fascinated by it. But I’ve always been renowned in school for being a bit strange, a bit of a nutter.”

* adi.bloom@tes.co.uk