I firstly separated the two words in order to go into detail on their individual meanings.
A vast desert of northern Africa extending east from the Atlantic coast to the Nile Valley and south from the Atlas Mountains to the region of the Sudan. During the Ice Age (about 50,000 to 100,000 years ago), the Sahara was a region of extensive shallow lakes watering large areas of vegetation, most of which had disappeared by Roman times. Introduction of the camel (probably in the first century a.d.) led to occupation by nomadic tribes who moved from oasis to oasis in search of water.
(Government, Politics & Diplomacy) a monarch who rules or reigns over an empire