Possible Clues:

• Northern African desert
• Arid region: I've found it right in middle of South Africa
• Desert covering much of north Africa
• Desert that covers much of Libya
• Desert home to the Tibesti Mountains
• Word from the Arabic for ''desert''
• Habitat for the addax antelope, which can go a year without drinking
• Home to about 90 oases
• Sarah travelling round a vast expanse
• Desert covering much of North Africa