Saudi Arabia is not exactly a plain; it is rather a plateau. It rises from sea level on the Gulf coast, near Jubail and the oil-producing areas, continues to rise gently until it reaches an area just before the coast near the Red Sea. On the mountains are the two holy cities: Meccah and Medinah. Somewhat between them is the vacation city of Taif. By law, non-Muslims are not allowed in either holy city, and there are armed checkpoints that ensure only Muslims get through.
The roads were strange. We would drive along a well-paved highway that would suddenly no longer exist as a highway, but would instead become a city street. More than once we had to ask for directions, which was an interesting trick when you don't speak Arabic. Usually some kind person would make gestures for us to follow him and he would lead us to where the highway began again.
It is a tenet of Islam that a good Muslim helps people in need. There is no question that many Muslims received much helping credit while we were traveling. I have many fine memories of Saudi Arabia. This is one of the best. Nice, helpful people and a fascinating culture.