The Rub’ al Khali (Arabic: الربع الخالي).
A really good book!
The Great Game: On Secret Service in High Asia by Peter Hopkirk.
“For nearly a century the two most powerful nations on earth, Victorian Britain and Tsarist Russia, fought a secret war in the lonely passes and deserts of Central Asia. Those engaged in this shadowy struggle called it ‘The Great Game’, a phrase immortalized by Kipling in his book Kim”.
David A Lockwood 