I have another post somewhere about this place they claim is The lost City of Ubar: known by various other names (Wubar, Wabar, Iram of the Pillars and Atlantis of the Sands mentioned by Lawrence of Arabia) but the more I visit, the more I think it lives by reputation & reality is something quite different.
It certainly held some significance for the Frankincense trade route but; looking at the site with mark one eyeball, it is small compared to Khor Rorī or Al Balid on the coast: a lot of wishful thinking going on me thinks.
Freya Stark sums it up.
When the explorer Freya Stark consulted the works of Arab geographers, she found a wide range of opinions as to the location of Wabar: “Yaqut says: “In Yemen is the qaria of Wabar.” El-Laith, quoted by Yaqut, puts it between the sands of Yabrin and Yemen. Ibn Ishaq… places it between “Sabub (unknown to Yaqut and Hamdani) and the Hadhramaut. Hamdani, a very reliable man, places it between Najran, Hadhramaut, Shihr and Mahra. Yaqut, presumably citing Hamdani, puts it between the boundaries of Shihr and San’a, and then, on the authority of Abu Mundhir between the sands of B.Sa’d (near Yabrin) and Shihr and Mahra. Abu Mundhir puts it between Hadhramaut and Najran.”
I paraphrase: With such evidence, it seems quite possible to find Wabar in opposite corners of Arabia.
David A Lockwood 
Reminds me of Rannulph Fiennes’ “Atlantis of the Sands” that I read many moons ago. That led me to his much more interesting “Where Soldiers Fear to Tread” about his time in Oman and the background to his novel (or is it?) “The Feather Men”.
Unfortunately, I found the first and last of the 3 books you mentioned, rather disappointing because of IMHO – questionable assumptions.
His ‘Where Soldiers…’ was very good, Oman in the 1950’s & 70’s. was a challenge for both the Omani and British military. Britain gained a lot of appreciation from Oman because of its commitment in those two wars.
I’d concur! The heart and minds aspect seems to be a big part of early SAS operations.