The Rub' al Khali (Arabic: الربع الخالي ar-Rubʿ al-Ḫālī, Empty Quarter) is the largest contiguous sand desert in the world, encompassing most of the southern third of the Arabian Peninsula. It is the cradle of civilization on Earth, containing the ruins of Ubar, an ancient city that predates human civilizations by at least 4,000 years.
The Rub' al Khali once holding the Ubari civilization has made locals, such as the Omani, overwhelmingly superstitious of the area. Tales of the area being cursed and forbidden to be in has propagated throughout the surrounding cultures to warn about the eldritch civilization that once existed in the Rub' al Khali nearly ten thousand years ago.
Guides were willing to take outsiders but due to their fear of the area are more likely to abandon those who stay too long in the forbidden areas. This was the case for Lorenzo Cabot and his party in their expedition to find Ubar when they ignored their guide's warnings who promptly fled at their first opportunity.
↑The Sole Survivor: "That's really interesting." Jack Cabot: "I'm glad to hear you say that. It's become my life's work.My approach is to combine a rigorous scientific method while keeping an absolutely open mind.So much has been closed off to us simply because people assumed they already knew the answers.My father excavated a city in the Rub'al Khali in Arabia which he dated to more than 4,000 years before the rise of any known human civilization.The structures and artifacts were... strange. Disturbing, even. Clearly not constructed for or by humans.I've spent my life trying to decipher what he uncovered." (Jack Cabot's dialogue)
↑The Sole Survivor: "I was intrigued by your theory about an ancient alien civilization." Jack Cabot: "Yes, if by "alien" you mean a non-human precursor to the commonly understood founding cultures -- Sumer, Egypt, Assyria. It was originally my father's theory. He believed that all of the earliest human civilizations shared some common parent that was unknown to history. Think of Atlantis - the myth of an advanced civilization destroyed by a cataclysm is shared by many widely separated ancient cultures.Eventually, he found was he was looking for - a lost city, buried beneath the sands of the Empty Quarter of the Arabian desert." (Jack Cabot's dialogue)
↑The Sole Survivor: "You said your father found a lost city?" Jack Cabot: "Yes. He spent years looking, and was widely ridiculed by the so-called experts. I'm ashamed to say even I doubted him.But in the end he found it: a lost city, buried in the sands of the Rub'al Khali, the Empty Quarter of Arabia.Millennia older than the earliest human civilizations. But with technology that seems to have surpassed our own.And yet, everything about it is... strange.Disturbing geometries, tools not made for human hands, carvings that hint at dimensions beyond our own..." (Jack Cabot's dialogue)
↑The Sole Survivor: "" Jack Cabot: "You wouldn't have. My father only made one expedition to the lost city, and his findings were never published.The clues were all there, scattered amongst the earliest civilizations... but he was the only one to understand what they meant.He followed them into the Empty Quarter of Arabia, to the nameless city buried in the sand like the mythical Atlantis beneath the waves..." (Jack Cabot's dialogue)