A team of intrepid walkers and their camels wearily marched towards the Qatari capital Doha, the last leg of a 50-day trek across the world’s largest sand desert.

They are on the verge of successfully retracing the historic 1,300-km route taken in 1930 by British civil servant and Arabist Bertram Thomas.

The three-man team walked from Salalah in southern Oman, through Saudi Arabia, to Doha, across a vast stretch of uninhabited land in the southern Arabian peninsula known as the Empty Quarter or Rub' al Khali.

Yesterday they set off at around 4GMT from a moonscape-like desert south of Doha to complete the final 30km or so of their epic journey.

Despite the threat of warring tribes and a constant struggle to find enough water, Thomas completed the journey in 57 days.

The modern-day trekkers led by Omani-based British explorer Mark Evans are hoping to complete the journey in fewer days.

Evans, 54, said he was in awe of the achievement made by Thomas and his team 85 years ago.

“I would say how humble we are about what those people achieved,” he said.

“They were completely on their own,” said Evans.

His team includes the great, great grandson of Sheikh Salih bin Kalut al-Rashidi al-Kathiri who completed the original journey with Thomas.

“Because it is my great, great grandfather, I wanted to recreate it,” said Sheikh Mubarak Saleh Mohamed Salah bin Kalut. “I am proud that he was part of the original team.”

Unlike Thomas, Evans and his fellow walkers have been able to use GPS and smartphones to communicate with the outside world, while two vehicles carrying water and provisions accompanied them during their voyage.

But like Thomas, they have also endured walking across enormous sand dunes in Saudi Arabia, searing day temperatures and cold nights and sleeping without a tent under the stars each evening.

“We look like an Egyptian sarcophagus each morning when we wake up, covered in sand,” said Evans, a fellow of the Explorers Club of New York, and The Royal Geographical Society in London.

As well as recreating the steps of explorers from the 1930, there is also a scientific element to the journey.

The team has found tools and discovered ancient Arabian script in Oman up to 3,000-years-old.

They have also completed a psychological questionnaire each evening for a study in “exercise environment psychology” being carried out at a British university, said Evans.

The team received help from all three countries they have trekked across from assistance at border crossings, to camels being supplied by the Qatari royal family.

These have proved the hardiest as Evans admits that modern-day camels, like humans, “have got a bit soft”.

The journey is set to end close to the Al Rayyan fort on the western fringes of Doha.