When this book was first published in 1958, Arabia was even then one of the least known corners of the globe. The foreigner was strictly forbidden from entering, except those with the Imam's personal consent, and then under close supervision. Foreigners were only allowed as far as the capital, and what lay beyond was practically unexplored. To Hans Helfritz the only hope of seeing the forbidden area was to make a secret journey, approaching it in disguise by the back door. He decided to reach the borders of the Yemen by a wide detour through the interior, crossing a desert previously considered impassable and still recorded on the maps as a blank. Beginning on the coast at the eastern extremity of the Gulf of Aden, he made his way through the Hadhramaut, the Rub' al Khali and the Yemen to the Red Sea, the first crossing ever of the south-western part of the peninsula. From this journey he brought back a fascinating record of adventure and exploration, together with many wonderful pictures of cities never before photographed.