Last time, Zhang Zian had taken the arc route of Cairo-Alexandria-Matruh-Siwa Oasis. In order to go sightseeing in Alexandria and Matruh, he'd chosen the route from Cairo along the highway westward and through Faiyum Oasis to Siwa Oasis.
If one went south rather than west at the fork in the road, it led to a famous scenic spot in Egypt, the Black and White Desert.
The Black and White Desert was made up of two adjacent deserts. One was the Black Desert, and the other was the White Desert. Many visitors to Egypt would visit it and spend the night in the desert, lighting bonfires, living in tents, eating barbecue, drinking beer, and enjoying the desert sunrise and sunset as well as the pure and pollution-free starry sky, which brought new experiences to people who lived in big cities.