Capital: Riyadh Area: One-third the size of the U.S. Topography: The 9,000 foot-tall highlands on the west slope as an arid, barren desert to the gulf. Population: 16,758,000 Ethnic groups: Arab tribes, emigrants from other Arab and Muslim countries. Language: Arabic Religion: 99% Muslim. Industry: Oil. Head of State: King Fahd, came to power in June 1982.