Out in the desolate Baal Thayfer – the "Place of Camel Droppings" – Mabkhot Al Amiry hefts his blade, choosing where to make the first cut. A breath of wind breaks the silence, rattling the papery bark of the tree in front of us with a sound like the wing-cases of dead insects. Mabkhot squats a little closer. With short, downward strokes he gently uses his manqaf – a broad chisel – to chip away a strip of bark, exposing orangey sap-filled wood.
As we watch, white droplets appear on the surface of the wound, swelling to form viscous globules. Mabkhot encourages me to touch one. It is sticky and resinous. The fragrance knocks my olfactory socks off – deep, complex, a bit like peaches, a bit like furniture, but instantly familiar. It smells like old churches.
This is frankincense country – the Dhofar region of southern Oman – home to Boswellia sacra, source of the ancient world's most highly prized commodity. For millennia people have scraped the bark of this scraggly tree, allowed its sap to harden into small nuggets, then picked them off and heated them over embers. Religious ritual across the Mediterranean and the East depended and, in places, still depends, upon thick, sweet frankincense smoke to transport supplications heavenwards.
At the height of the Roman Empire, Dhofar was exporting immense quantities of frankincense, by ship to Yemen and thence up the Red Sea, and by camel caravan overland to Petra and the Mediterranean. Astride that caravan route, at the southern edge of the vast Empty Quarter, lies the fabled trading entrepôt of Ubar, lost in the desert for over 1,500 years and rediscovered less than 20 years ago by a team led by British explorer Sir Ranulph Fiennes.
After the encounter with Mabkhot, my Dhofari guide Ali Al Shahary takes us off-road into the sands of Shisr to reach it. Fiennes had become obsessed with finding Ubar while stationed in Dhofar in 1968. In his book Atlantis of the Sands, he describes how it took years of searching before Shisr emerged as the likeliest candidate. His team began digging in 1991. Soon, unique pottery, glassware and fragments of a 2,000-year-old chess set confirmed the discovery of a major centre of international trade.
I can see how they almost missed it. The site is only half the size of a football field. A few walls stand above a crater several metres across, formerly the city's water source. This collapsed around AD400, destroying Ubar and the surrounding oasis. The Koran mentions the calamity, talking of the earth being "cleaved open".
Now, despite the drama – and the fabulous wealth of Ubar's former inhabitants – Ali shows me the site in five minutes flat, pointing out the stumps of towers and peering into the gaping cavern. At the highest point of the ruins, I sit to flip through my copy of Atlantis of the Sands.
"Ah, Bakheit," says Ali. He points at a photo of a young man who, the caption reads, helped Fiennes dig 18 years ago. He slides his mobile phone open and does some scrolling. "I have his number. Would you like to meet him?"
At a dusty roadside café in Thumrait, as Indian truck drivers shovel handfuls of soupy rice, Bakheit bin Abdullah sips his sweet, milkless tea. Two decades have been kind to him: he is a little plumper, neater, but with the same sly twinkle. "More British people should come here," he says. He recalls meeting Wilfred Thesiger in the early 1970s. I ask about Fiennes and he pulls a tough-guy face. "He was a hard worker. I'd like to see him again."
Down the hill from Thumrait, the easy-going Dhofari capital Salalah is another, lusher world, the only sliver of Arabia to receive the Indian Ocean monsoon. Ali and I laze under palms and papaya trees, sipping water from fresh-cut coconuts while the surf crashes. Beside the ancient frankincense port of Al Baleed I explore Salalah's state-of-the-art historical museum and grip the wheel of a baghla, an Arab sailing vessel, reproduced life-size. Along the coast at Sumharam, another Roman-era frankincense port, Ali shows me the ruined temple of the moon god Sin, high above a quiet creek once crammed with merchant shipping.
After sunset, Abdullah Al Mahary, stallholder in Salalah's souk, offers me a pellet of frankincense. "Good for the stomach," he says, chewing thoughtfully. It tastes like it smells: pungent and impossibly exotic. At more than £80 a kilo, his golden, almost luminescent Hawjari frankincense, from the trees of Wadi Hawjar, an isolated valley behind Sumharam, is top quality. Lower grades – Najdi, Shazri, Shaabi – are darker and coarser, down to imported frankincense from Somalia, at £2 a kilo. Abdullah Saidi, a customer visiting from Abu Dhabi, nudges me. "This Hawjari is the best," he smiles. "We burn it every day in the house."
The souk's aroma is extraordinary: every shop is selling frankincense, scented wood chips known as bakhoor, perfumes, oils – and myrrh. This glassy and bitter-smelling tree resin, burnt in the ancient world at funerals, is nowadays, prosaically, a decongestant for children. Anwar Al Muraza sells me a tub of Somali myrrh for pennies. Oman produces its own myrrh, he assures me, from groves near Harwib on the Yemeni border, but it hardly ever comes to market.
Ali forges onwards into the gold souk, introducing me to Mohammed Zubair – originally from Lahore but 26 years in Salalah. "We still make Omani styles, using local goldsmiths," Mohammed says, and reaches below the counter to show me the latest designs.
Mohammed is showing me gold. I'm carrying a bag of frankincense from Mabkhot. And in my pocket rattles Anwar's myrrh.
Salalah could make a wise man of me yet.
Travel essentials: Oman
Oman Air (0844 482 2309; omanair.aero) flies from Heathrow to Salalah via Muscat.
Crowne Plaza, Khandaq Street, Salalah (00 968 2323 5333; cpsalalah.com). Double rooms start at 52 rials (£83), including breakfast.
Contact guide Ali Al Shahary (00 968 9540 1513; email: firstname.lastname@example.org).
Oman Tourism: 020-8877 4524; omantourism.gov.om