For a steel bar to glow with the fiery orange of a setting desert sun, you need to heat it to just under 500C.

 Apply that near-molten bar then to human skin and the result is a sudden, terrifying shock – a sizzling evaporation of flesh and nerves, a jolting, apocalyptic pain that leaves a lifetime’s scar.

 But that’s not all it does, says Salam Salimun Al Mahi, an octogenarian Jebali Bedouin practitioner of the dying art of wassm – branding – as we sit in the shade besides his house, here in the isolated village of Rabkut, in Oman’s southern province of Dhofar.

 Taking the foot-long steel bar he has used for generations, he demonstrates excitedly how holding its glowing end against a person’s scalp is also a cure for headaches.

 For back pain, too, a burn to the lower calf muscle will do the trick; for shoulder aches, three slashes of the branding iron across the middle back. For leg pain, here and here – he flashes the steel rod – you hold it across the ankle of the opposite foot.

 “The more it hurts, the better the cure,” Salam’s grandnephew, Mohammed, says, provoking a nod of approval from his great uncle.

 Around us, the afternoon wind has begun to pick up, blowing mercifully along the sandy tracks that separate the town’s houses, and rustling the slight leaves of the solitary ghaf tree in Salam’s yard.

 We have just travelled from Salalah in Mohammed’s giant SUV, rolling over the lush, green mountains of the Jebel Qarra – still foggy in the almost miraculous mists of the khareef, the tail-end of the Indian monsoon that touches along the coast of Dhofar.

 From there, we have travelled on across the rocky desert that comes next, heading further inland, as the increasingly despairing landscape bleeds into the engulfing sands of the Empty Quarter.

 “Out here, in the old days, there were no doctors,” says Mohammed, “so my great uncle was the doctor, the healer. He uses wassm, which is not called wassm here, but kowey in Arabic, or mashat, in the local, Mahiri language.”

 Salam has two steel rods – the thinner one he uses on people, the thicker one is for camels.

 “It’s the same?” I ask.

 “Sure,” they both nod.

Salam learnt his craft from his father, who learnt it from his grandfather, and so on back. He makes a circle with his hands as he describes the endless passing on of this knowledge, propping himself up with a wooden stick as we sit on the shaded, hard ground. There is a slight smell of frankincense mixing with the dusty-dry desert air.

 “Do your grand children know about kowey?” I ask.

 “No, not so much,” Salam answers. “The young are a bit afraid of the pain.”

 “Sometimes, nowadays, they only do a small touch, quickly,” adds Mohammed. “But it’s not as good,”

 After they have both shown me their scars – white streaks across Salam’s old, balding scalp, and black wounds across Mohammed’s back – we are silent for a while.

 “Do you have any pain you would like my great uncle to fix?” Salam’s grand nephew then asks me.

 I look at the blackened steel rod before me. Suddenly, the ache in my left foot seems to have completely gone away, and paracetamol seems such a friendly invention.

 “No,” I say. “Perhaps it’s time we headed back?”